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A novel way to massively improve the SQ of computer audio streaming

The Computer Audiophile

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Most important: please realize this thread is about bleeding edge experimentation and discovery. No one has The Answer™. If you are not into tweaking, just know that you can have a musically satisfying system without doing any of the nutty things we do here.

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3 hours ago, mikicasellas said:

Dave,

 

Do i need to put an SSD on the NUC in order to install Roon, or can i just do it from the USB stick selecting in AL menu "Roon Server"?

USB stick headless; in BIOS turn on speed step, set power limits to max , boot to extreme 2 , run real time in extreme. For 10k of tracks it took

about 30 minutes to scan library, then about 4 hours to analyze all tracks with 4 cores enabled. Once done enable run from RAM.  The only additional cost I incurred

was bumping RAM from 8 to 16gb because it looked like I only had 1gb of free RAM using RAM boot with an 8gb configuration, and Roonserver


Regards,

Dave

 

Audio system

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3 hours ago, mikicasellas said:

Dave,

 

Do i need to put an SSD on the NUC in order to install Roon, or can i just do it from the USB stick selecting in AL menu "Roon Server"?

 

28 minutes ago, Chopin75 said:

I think USB stick should work  fine but internal SSD should work best

 

The reasoning behind loading from a USB stick is that once it goes into RAM you can pull it out. That means no Optane as a hard drive, no SSD, whatever to introduce noise. 


Digital chain: Synology DS1815+ -> Linear Solution OCXO switch-> Custom 2016 Server (sCLK-EX modified motherboard, Mutec REF 10)-> AL NUC NA->  Holo Spring L3 -> Audio Research LS28-> Benchmark AHB2 -> Paradigm Persona 9H, JL Fathom sub

Power: Paul Hynes SR7, Uptone LPS-1.2, sPS-500, Topaz 91001-31 Isolation Transformer

Analog chain: VPI Prime with Ortofon Quintet Black cart -> Simaudio Neo 310LP-> Audio Research LS28-> Benchmark AHB2 -> Paradigm Persona 9H

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A device that disconnected (the gnd, or whatever is needed to prevent noise transfer) of the SSD each time a block of tracks filled up RAM would accomplish the same as pulling the USB stick out.  It could then re-connect when RAM contents were nearing depletion.  And it would be much more convenient too...

 

Who knows USB-C or Thunderbolt really well?


"The overwhelming majority [of audiophiles] have very little knowledge, if any, about the most basic principles and operating characteristics of audio equipment. They often base their purchasing decisions on hearsay, and the preaching of media sages. Unfortunately, because of commercial considerations, much information is rooted in increasing revenue, not in assisting the audiophile. It seems as if the only requirements for becoming an "authority" in the world of audio is a keyboard."

-- Bruce Rozenblit of Transcendent Sound

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9 hours ago, mikicasellas said:

Hi Gents,

 

I am considering which step to follow in this NUC (endpoint/server) venture:

 

I already have the NUC7PYCH with AL booted in RAM and using a MacMini (late 2012) as a Roon server.

 

Cause i go step by step on a budget, i am not sure if my next logical step should be getting a NUC Intel NUC7i7DNHE or a more flexible PC in order to replace the Mac mini as the Server or keep the Mac mini and replace the NUC7PYCH with the NUC7i7DNHE to elevate SQ.

 

What do you guys think would be the reasonable step to follow? for those who has tried both experiences?

either way i cold make another replacement later being on the endpoint or the server, just like to know where to put the coin now wisely.

 

Can anyone share also the way to make the Bridge between the two devices?

 

Regards to all

 

 

Not a big fan of Mac as music server, too noisy and would it be too underpowered for 2012 CPU? I presume u use LPS for the mac which could be less noisy, fanless NUC possibly better 

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21 minutes ago, Johnseye said:

 

 

The reasoning behind loading from a USB stick is that once it goes into RAM you can pull it out. That means no Optane as a hard drive, no SSD, whatever to introduce noise. 

Sorry, I was jumping between euphony OS and this tread which is about AL, so I thought we were talking about Euphony. Ignore my previous comment then. (Euphony runs better on SSD and cannot run in RAM )

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1 minute ago, Johnseye said:

 

 

The reasoning behind loading from a USB stick is that once it goes into RAM you can pull it out. That means no Optane as a hard drive, no SSD, whatever to introduce noise. 

Logic is a bit different with a 1 box NUC AL/Roon solution, the library media drives become your biggest pain... they generate noise and you have to leave them connected. 

Have to solve that before unplugging an idle USB stick can be heard.


Regards,

Dave

 

Audio system

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15 minutes ago, Ralf11 said:

A device that disconnected (the gnd, or whatever is needed to prevent noise transfer) of the SSD each time a block of tracks filled up RAM would accomplish the same as pulling the USB stick out.  It could then re-connect when RAM contents were nearing depletion.  And it would be much more convenient too...

 

Who knows USB-C or Thunderbolt really well?

Seriously? Can anyone hear that noise when it is loaded ? Would a pause before the start of track help? Though this won’t work if tracks are joined together continuously. Separate LPS on the SSD would help? 

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3 minutes ago, davide256 said:

Logic is a bit different with a 1 box NUC AL/Roon solution, the library media drives become your biggest pain... they generate noise and you have to leave them connected. 

Have to solve that before unplugging an idle USB stick can be heard.

 

1 box meaning all your music is on it as well? Otherwise it doesn't matter. Everything can load into RAM with AL except the music library unless you stream and use a NAS. NAS vs USB drive is another topic all together. 

 


Digital chain: Synology DS1815+ -> Linear Solution OCXO switch-> Custom 2016 Server (sCLK-EX modified motherboard, Mutec REF 10)-> AL NUC NA->  Holo Spring L3 -> Audio Research LS28-> Benchmark AHB2 -> Paradigm Persona 9H, JL Fathom sub

Power: Paul Hynes SR7, Uptone LPS-1.2, sPS-500, Topaz 91001-31 Isolation Transformer

Analog chain: VPI Prime with Ortofon Quintet Black cart -> Simaudio Neo 310LP-> Audio Research LS28-> Benchmark AHB2 -> Paradigm Persona 9H

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3 hours ago, Chopin75 said:

Separate LPS on the SSD would help?

 

Or separate low noise  +5V 1A voltage regulators powered from the internal +12V supply for each SSD.


"If you can't hear the difference between an original CD and a copy of your CD,

you might as well give up your career as a tester. The difference between a reconstituted FLAC and full size WAV is much less than that, but it does exist. - Cookie Marenco"

 

PROFILE UPDATED 18-06-2019

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For those that like all the extra boxes ;) The JCAT Net card can be powered using an external 5V (>=1,5A) power source. The upcoming Sonore OpticalModule will accept 5-9V so in theory it’s possible to power both using one PSU set to 5V and an Y-cable.

 

I’m currently using a cheap TP Link MC220L to one of my server NIC’s, the other NIC (both bridged) is connected to the NUC endpoint. Both will be replaced soon by the JCAT Net card. I may replace the TP Link with an OpticalModule when it becomes available to still enjoy the benefits of the full galvanic isolation fiber optics offer.

 

Then later I could also use the etherREGEN between the server and endpoint. With the other audiophile switches like SOtM, TLS, ... this seems to be the preferred setup.

 

Another option would be to sacrifice the bridge functionality, use the fiber input of the etherREGEN for the connection to the main network, connect the end-point to the isolated 100mbps output port of the etherREGEN and the server to a RJ45 port on the other side of the ‘isolation moat’. I would then not need the opticalModule.

 

One could also use two etherREGENs; one in front of the server and one in between server and endpoint.

 

So many exciting options for us audiophiles nowadays, good times!! :)

 

 

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2 hours ago, Dutch said:

For those that like all the extra boxes ;) The JCAT Net card can be powered using an external 5V (>=1,5A) power source. The upcoming Sonore OpticalModule will accept 5-9V so in theory it’s possible to power both using one PSU set to 5V and an Y-cable.

 

I’m currently using a cheap TP Link MC220L to one of my server NIC’s, the other NIC (both bridged) is connected to the NUC endpoint. Both will be replaced soon by the JCAT Net card. I may replace the TP Link with an OpticalModule when it becomes available to still enjoy the benefits of the full galvanic isolation fiber optics offer.

 

Then later I could also use the etherREGEN between the server and endpoint. With the other audiophile switches like SOtM, TLS, ... this seems to be the preferred setup.

 

Another option would be to sacrifice the bridge functionality, use the fiber input of the etherREGEN for the connection to the main network, connect the end-point to the isolated 100mbps output port of the etherREGEN and the server to a RJ45 port on the other side of the ‘isolation moat’. I would then not need the opticalModule.

 

One could also use two etherREGENs; one in front of the server and one in between server and endpoint.

 

So many exciting options for us audiophiles nowadays, good times!! :)

 

 

can you do a diagram of all these boxes linked up?

.........

JCAT Net card

Sonore Optical Module

TP Link MC220L

server NIC’s

NUC

Sonore Optical Rendu

Uptone Ether REGEN

Uptone Iso Regen

SOtM switches

sCLK-EX

tx usb ultra

TLS switches

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27 minutes ago, romaz said:

It's been a long time and so forgive me if I have a lot to say.  As I indicated in one of my last posts back in 2018, I wouldn't post again unless I felt I had something meaningful to offer.  I have received a lot of inquiries about the status of my audio setup and I apologize as I have not responded to most of these inquiries due to time constraints.  To be honest, since I started this thread back in 2017, my system has been in continual flux but the time has come hopefully to settle down for awhile and so I felt it was finally time to share the status of my setup and to offer some personal observations based on my comparison testing.  This marks my first public post since CA became Audiophile Style.  I miss just being able to say "CA" and having the audiophile community know what I am referring to.

 

As always, what I have to share are personal observations and opinions based on my sensitivities and personal preferences.  I have no financial motivations.  I have 2 systems at home and what works well in one system doesn't always work well in the other.  In other words, YMMV.

 

As for my 2 systems, they are as follows:

 

In my home office, I have a pair of near field desktop monitors that were custom made for me by Louis Chochos of Omega Speaker Systems based in Connecticut.  They cost me <$2k and they remain one of the highest value purchases I have ever made.  They are comprised of Louis' high efficiency, crossover-less Alnico drivers and excel in delicacy, nuance, and tone.  I am continually amazed by how well these drivers express the subtlest textures.  I used to own a pair of custom made Voxativs that were even more resolving and oh so velvety smooth but also a tad bright and not ideally suited for long term near field listening and so those are now gone.  Paired with a fast JL Audio Fathom F110 V2 subwoofer and driven directly by a Chord Hugo TT2 / Hugo M-Scaler, I find this Omega setup to be very transparent, highly resolving, non-fatiguing, and transfixing.  I own or have owned many fine headphones over the years (SR-009, HD800/HD800S, HE-1000 V2, Abyss 1266, LCD-4, Focal Utopia, Dharma D1000, TH-900) and when my children were living at home before they moved off to college, I found myself forced to headphone listening at night but my headphones have been collecting dust for some time because I have found my Chord DAC directly driving these Omegas to be that much more engaging, even at low listening volumes. 

 

With my youngest son having moved out of the house and onto college late last year, my big listening room is where I do most of my listening these days.  This room has been home to a lot of different speakers over the years and for most of the previous year, I was using a pair of large Martin Logan Renaissance 15A hybrid electrostats.  Typical of line source, dipole speakers, these Martin Logans cast a giant ambient sound stage and are wonderful for recreating large venue performances at full scale.  Driven by a Pass Labs X350.8 amp and XP-22 preamp, this setup excelled in beauty but ultimately lacked in resolution and transparency even when fronted by my Chord DAVE DAC with M-Scaler.  These giant electrostat panels, while very fast and with exceptional clarity, created a softly focused image and so point sources like a solo cello or a solo vocalist sounded too diffuse, too tall, and too wide for my tastes, regardless of speaker position.  As I made tweaks in my upstream setup, I could hear changes, however, I could hear these changes much more succinctly with my inexpensive Omegas and so for someone who values transparency, this drove me nuts.  Imaging and focus improved considerably with a switch from Pass Labs amplification to a more resolving Luxman M-900U/C900U and ultimately to Soulution amplification.  Imaging and focus further improved dramatically when I moved from a Shunyata Triton V3 to a Sound Application TT-7 line conditioner by Jim Weil but despite these improvements, I eventually came to the realization that I was not meant for line source speakers like electrostats or planars like my brother's Maggies.  Don't get me wrong, these are wonderful types of speakers with tremendous appeal but my time with the Martin Logans have better educated me as to the type of listening I prefer and so I have moved on to point source speakers once again in my large listening room, specifically the Wilson Alexia 2s.

 

I offer the above details for the following reason.  It's important to understand the context by which my observations and opinions are based and the priorities that I value as your priorities may be different.  I'm guessing that we all claim live music as our reference and yet it's interesting to see how we each vary in our approach to achieving the recreation of a live performance.  Because today's technologies remain incapable of faithfully reproducing a live musical performance and because we each are constrained by a budget, it helps to know what type of listener you are to understand which compromises you should accept above others.  My goals, simply stated, are resolution and transparency in the absence of harshness.  I aspire to beauty, organic, natural, and musical just like everyone else but these qualities are more in the eye (or ear) of the beholder and are not easy to define.  I tend to run from things that are described as warm (meaning slow), thick, heavy, euphonic, or lush.  Not that I don't like warm or lush, I just don't want everything sounding warm and lush if warm and lush aren't in the recording.  Just not me.  I find that if you can successfully address harshness at every step in your chain, there's usually no need to embellish or to colorize.

 

Moving on, here's a story about listening that some will find interesting.  There are 2 types of listening that most of us do.  There is critical listening where we focus on what we are hearing hoping to dissect the qualities of a performance, recording, or some piece of equipment and then there is pleasurable listening where the goal is to relax and to escape.  Given the choice, I'm sure most of us would prefer the latter.  Almost a year ago to this day, I hosted Rob Watts (who needs no introduction), Jay Luong (lead reviewer for AudioBacon.net), and Jim Weil (owner of Sound Application and designer of SA's line conditioners) in my home for a series of listening tests.  What I respect about these 3 gentlemen is that they are each highly educated and accomplished electrical engineers but also passionate music lovers.  It has been my experience that most engineers aren't true music lovers, don't know how to critically listen, or worse, they're closed-minded with fixed ideas about how digital electronics are supposed to sound based on theory alone.  Not these gentlemen.  

 

Rob had come all the way from Wales and brought along prototypes of M-Scaler and Hugo TT2 for us to listen to and for the better part of 5 days, we conducted a series of critical listening tests.  We did a lot of listening, both sighted and blinded, to Rob's prototypes, to different DACs, amps, cables, line conditioners, and speakers.  While it was a lot of fun to hang out with these individuals, our listening sessions were often more tedious than enjoyable.  We listened to select portions of Mahler's 1st symphony so many times that I couldn't listen to this symphony again for months.  What I found fascinating but not surprising is that while we each heard differences, we heard them differently and had different preferences.  Jim Weil had a strong aversion to anything bright.  Rhodium and silver-plated copper are Jim's enemies and he could sniff them from a mile away.  Jay Luong was especially sensitive to tone and timbre and would gladly trade detail for warmth.  Rob was particular to depth.  An organ that was 30 feet away had to sound as if it was 30 feet away.  Everything else was secondary and so not surprisingly, his DACs excel in depth accuracy.  My sensitivities are more toward transient response and the air and space around voices and instruments.  I also crave variation over harmony.  Even 2 Stradivariuses should never sound exactly the same and a system that makes them sound exactly the same simply isn't transparent enough.  We are who we are and so gear will speak differently to each of us.

 

Single box server vs server + endpoint

 

There are compelling examples to support either strategy.  In the perfect world, I would love to have the convenience of a single box solution but I have yet to hear a single box solution that I prefer over a multiple box solution.  With multiple boxes, there is the option for finer level tuning which I will discuss further but ultimately, it comes down to how well each box can be powered.  If all I can come up with is a single good PSU, than a single box server is all that I will aspire to.

 

The Endpoint

 

Those who have followed this thread from the beginning know that its original goal was to figure out ways to improve endpoints like the sMS-200 or microRendu.  It's amazing how endpoints have evolved since January 1, 2017.  The concept behind the endpoint was to create a low noise rendering device to interface with the DAC that isolates against noise generated by a powerful computer server.  Low noise was the rationale for using low power processors like ARM-based CPUs and even Celerons.  It was also the premise behind the avoidance of other noisy components like SSDs and switching power supplies.  While some of these principles have passed the test of time, others have not, at least not to my ears.  Low power CPUs are not necessarily what sound best.  How else can I explain how an i7 NUC board with its noisy switching regulators can sound better than an ARM-based sMS-200ultra or ultraRendu?  How else can I explain how an i7 NUC can sound better as I ramp up CPU clock frequency?  It's completely counter-intuitive but it suggests that aside from noise, there is performance to consider and sometimes performance requires power and sometimes performance is more important than low noise.  To my ears, an i7 has the potential to sound more spacious, fuller, and more dynamic than a Celeron or ARM-based CPU and the number of physical cores, CPU frequency and size of the CPU cache seem to matter.  The downside of the i7 is that they are potentially more challenging to power well.

 

Thus far, I have tested 5 NUC boards comprised of either a Celeron, i5, or i7 CPU and ranging from 2-cores to 4-cores and from 2MB of standard CPU cache to 8MB of SmartCache.  The best sounding board I have heard thus far is the NUC7i7DNBE based on an 8th generation i7 that I first discussed a few months ago.  

 

image.png.1248fa6cd8d54352c32906922534aeed.png


I am open to the idea that a more powerful, non-NUC device could sound even better as an endpoint but once again, powering it would be the challenge.  Here is the Asrock IMB-1215 which will be released to the U.S. in a few months.  

 

image.png.096ea2e455daae848b81db5dc5091cb9.png

 

It is a mini-ITX board that can accommodate an 8th or 9th generation i7 and with an open PCIe slot that can be powered by a single 19V rail and so I find this board to have intriguing possibilities.


SOtM has reportedly designed an i7-based motherboard from the ground up with high level clocks that can be powered by a single 19V PSU.  I very much look forward to trying out this board.  

 

The NUC7i7DNBE when purchased as a board are more difficult to come by and also more expensive at a price of around $650 USD.  Ironically, the NUC7i7DNKE NUC kit, which houses a NUC7i7DNBE board within a standard Intel chassis are much more readily available and cost $100 less.  I just purchased one a few weeks ago and it took all of 5 minutes to explant the NUC7i7DNBE board from the chassis.

 

The NUC7i7DNBE has the option of being powered by a 12-24V PSU and higher voltage DEFINITELY sounds better to me.  Bigger and more dynamic.  It also has the option of being powered via either a 2.5mm x 5.5mm barrel connector or 2x2 mini Molex connector.  With 2 NUC7i7DNBE boards on hand, I was able to recently do a direct A/B and powering via the 2x2 Molex connector sounds very slightly better.  

 

image.png.42dde319018b0f21cf20414864175b14.pngimage.png.e3ada1d593fccde913cd88322d88cad9.png

 

As for power supplies, I could not successfully power a NUC7i7DNBE board with a single LPS-1.2 at 12V even though my Kill-a-Watt meter suggests this board never consumes more than 8 watts during bootup.  I could get it to post to the BIOS screen but even with Turbo and Hyperthreading turned off and with only 4GB of RAM installed, I could not successfully boot into AudioLinux from a USB stick.  I purchased a special serial Y-cable from Ghent Audio and this allowed me to combine two LPS-1.2s and this worked.  The cable that I had Ghent make for me is comprised of high quality Neotech 18g 7N OCC copper and so I spared no expense to get it as I was very excited by the prospect of being able to power the NUC with 24V using two LPS-1.2s set at 12V each.  

 

Unfortunately, for reasons that remain a mystery, I could not get this to work.  Each time, one of the LPS-1.2s would start to blink red during the boot process and turn very hot.  I own three LPS-1.2s and regardless of which one I swapped in, one of the LPS-1.2s would start to blink red and it was not always the same LPS-1.2 that would give out.  When I kept one LPS-1.2 at 12V and switched the other to 9V (12V + 9V = 21V), this somehow worked and the NUC booted just fine.  19V (12V + 7V) also worked.  The problem with using two LPS-1.2s in serial is that they don't sound good at all and this was very disappointing.  In fact, I found better SQ powering the NUC with the 19V rail from my HDPlex which came as a surprise.  It appears that using 2 or more LPS-1.2s in serial is not a good thing to do.  The NUCi7DNBE also likes headroom and the LPS-1.2's 1.1A of headroom is a limitation.  To hightlight the importance of headroom further, a 12V SR4 sounds very good powering this NUC but a 12V SR7 with its greater headroom sounds even better.  

 

Beyond headroom, the avoidance of any voltage drop is also very important and a 12V DR (double regulated) SR7 sounds better yet although I am getting my very best SQ with this NUC powered by a 19V SR SR7 rail.  With this NUC powered by the 19V rail from an HDPlex 400W ATX LPSU, while the SQ is not in the same league as an SR7 or even the SR4, it is much less harsh than the stock 19V switcher that Intel provides and so the HDPlex is more than just a passable option.  The JS-2 or a bespoke PSU from either Sean Jacobs or Adrian Wun at TLS could be even better options but at a cost.  As I stated above, the downside of the i7 is that they are potentially more challenging to power well but I do feel the rewards are there.

 

As for clocking, not surprisingly, this makes a significant and worthwhile difference.  I had the TLS DS-1 on hand for a few months and it's single OCXO reportely replaced 3 clocks on this board (system, Ethernet, USB).  

 

image.png.fefaa8c14bc9a926e96a39b56a626a91.pngimage.png.7a7ea9786776341334fd5205250ca4a1.png

 

While much has been made about the mediocre performance characteristics of the Connor-Winfield OCXO that Adrian at TLS likes to use for all of his products, the removal of 3 noisily powered clocks from this board and replacing it with a cleanly powered clock even if that clock is of suspect performance has paid significant dividends.  I had a stock NUC7JYH board with its Celeron J4005 CPU on hand and it is the very same board and CPU that Adrian used for the DS-1.  Direct A/B revealed a significant uptick in detail clarity and spaciousness with the DS-1.  Compared against my stock NUC7i7DNBE, this superior detail clarity was still very much evident although I found the i7 NUC to sound more spacious still.  Regardless, I heard enough to know that it would be worthwhile to send my i7 board to SOtM for clock replacement and indeed, it has been worthwhile.  To have replaced the 4 replaceable clocks on this board has resulted in a notable decrease in harshness resulting in cleaner transients, better definition, more accurate timbre, and a greater sense of space.

 

image.png.763d8f27972d42475ce85aa6a8087920.png

 

However, the benefits of clocking have to be placed in proper perspective.  To my ears, the power supply still makes the bigger difference.  I have the benefit of having 2 NUC7i7DNBE boards on hand (one is stock and the other has been reclocked) and this has allowed me to make careful A/B comparisons.  With the stock i7 NUC powered by a 19V rail from my SR7, I am getting better SQ overall than the SOtM-modified NUC powered by the 19V rail from the 400W HDPlex.  If forced to choose, the choice would be easy.

 

The Server

 

With my inaugural post on this thread, I had described my observations about how LAN bridging resulted in increased transparency of the endpoint to the upstream server.  While the mechanism for why this improves transparency remains unsettled, with bridging, it was clear to me that the quality of the server mattered.  With the release of the SOtM sNH-10G switch last year, I reported that I was no longer able to differentiate between the Zenith SE and my noisy 12-core Xeon-based Mac Pro when either one was used as a Roon server.  But that was before AudioLinux came into the picture which allowed me to play with CPU frequency settings and this has made all the difference.  The Zenith SE houses a powerful and low noise PSU but it is mated to a very weak Celeron while my Mac Pro utilizes a noisy switching PSU mated to a much more capable 12-core Xeon with a giant CPU cache.  Without any OS manipulation of the CPU, cursory A/B comparisons between the two yielded no significant difference to my ears suggesting that the sNH-10G had effectively blocked the higher noise that was being generated by my Mac Pro.

 

But what would happen if I pushed my Mac Pro's CPU clock from it's base idle frequency to max turbo levels?  Of course, this is the beauty of AudioLinux and it has proven to be a very useful learning tool.  With higher CPU frequency, dynamics goes up but at the expense of subtlety and nuance and with progressively increasing harshness and the sNH-10G is incapable of completely isolating against these changes.  I have read commentary that the upcoming opticalRendu will supposedly be completely immune to the virtues of the upstream server.  I suspect this is probably the goal of the upcoming EtherREGEN also.  Well, I believe this is both naive and wishful thinking and so people will need to adjust their expectations appropriately or else they will be disappointed.  

 

I say this because I currently have 2 SOtM sNH-10G switches in my possession and I can tell you that while 1 switch makes a very big difference, 2 switches make an even bigger difference.

 

image.png.80e34c99ffb137de51da60568301efc3.png

 

What is nice about these switches is that they have both standard RJ-45 Ethernet ports as well as optical Ethernet ports and so with these switches connected by a single-mode fiber optic cable, here is what I found.

 

image.png.a8a736a11fded6799de4371be4e4518a.png

 

With the optical cable compared against a 50+ foot Blue Jeans Cables CAT6A Ethernet cable, the noise floor with the optical cable was noticeably lower and there is a clear preference for the optical connection.  With the optical cable compared against a 22-foot Belden CAT6A cable with JSSG360 shielding that was made for me by Ghent, the gap was smaller but there was still a slight preference for the optical cable.  With the optical cable compared against a heavily shielded 1.5m SOtM dCBL-CAT7 cable, the noise floor was equivalent (at least to my ears) but tonality with the SOtM cable sounded more natural.  The optical cable sounded a touch thin and bright in comparison and so in this instance, the copper Ethernet cable sounded better.  Regardless, in each and every comparison, optical or otherwise, if I varied CPU frequency, I could hear differences in the server.  The server still ABSOLUTELY matters and this is because it's not just about noise, there is also the matter of performance and it would appear that RoonServer likes horsepower.  At this time, the delta I am hearing from my best server setup to my worst server setup is about the same as the delta I am hearing from by best endpoint setup to my worst.  In other words, my current stand is that the server matters as much as the endpoint.

 

CPU

 

My testing has shown me that modern CPUs are preferable to older generation CPUs  A few generations ago, an i7-4790 yielded a TDP of 84w with 4-cores/8-threads, 8MB of SmartCache and CPU turbo speeds reaching 4GHz.  Today, an i7-8700T yields a TDP of only 35w but offers 6-cores/12-threads, 12MB of SmartCache and CPU turbo speeds reaching the same 4.0GHz.  Basically, more performance with less noise and A/B comparisons between these 2 CPUs reveal exactly that.  An 8700K houses potentially even greater performance with a max turbo rating of 4.7GHz using better binned parts according to Intel and so I decided to compare this against the 8700T.  

 

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Ultimately, it didn't seem to matter since I heard no benefit clocking either of these CPU beyond 3.8GHz when powered by the HDPlex 400W ATX LPSU due to harshness but who knows what would happen if I had a better ATX PSU on hand?  I have explored such a PSU with both Adrian Wun of TLS and Sean Jacobs but the cost of a "no compromise" ATX PSU from these gentlemen will run somewhere in the $4-5k range. Regardless, the CPU matters and if I were to build another server, I would probably go for a standard i7-8700 since they're more readily available and less expensive then either the 8700T or 8700K.

 

Motherboards

 

My testing has shown me that the motherboard matters also.  Borrowing a page from Pink Faun's book that gaming boards can sound better, I decided to compare a standard Asrock Z370M-ITX/ac motherboard against an Asrock Z390 Phantom Gaming-ITX/ac motherboard.  

 

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First of all, I only looked at Intel boards since it wasn't clear to me that an AMD board was compatible with Optane memory.  Second, I specifically targeted the Z370/390 chipset because these chipsets were capable of running the latest generation i7s (both 8th and 9th gen).  The Z390 board happened to be designed for gaming meaning they were engineered to be overclocked.  As such, this gaming board has an 8-layer PCB with a whopping 8oz of copper to maximize conductivity and to enhance the ground plane.  This board also has beefier heat sinks to improve heat dissipation and a more robust VRM (voltate regulator module) to make sure the CPU is never starved of current.  While the differences weren't large, the gaming board had more substance to the sound stage with greater authority to its presentation but not to be completely outdone, the Z370 board had a touch better finesse and subtlety.  The point is that even these more minor differences were easily audible in the server.

 

SSD vs Optane

 

Just for kicks, I decided to compare a 58GB Optane card against a Samsung 500GB 960 EVO NVMe SSD in the M.2 slot of the Asrock board.  This was a very brief comparison because it didn't take long to realize how much more harsh the SSD sounded even with all of my isolation schemes in place.  It's amazing how many commercial music server manufacturers continue to use SSD drives in their servers as if powering an SSD cleanly somehow addresses this harshness when it does not, at least not to my ears.  I suppose you get used to the harshness over time but an SSD is about the worst thing I can imagine putting into a music server with the super fast NVMe drives sounding the harshest of all.  As some may recall, in previous testing, I found the older, slower SATA II SSDs (especially the SLC variety) to sound less harsh then the newer, faster SATA III SSDs although the faster SATA III SSDs made music sound more alive and more immediate and so there was a trade off.  It would appear that the Optane cards have the best of both worlds and so hats off to Larry for introducing us to the Optanes.

 

I have read comments about how running AL in memory doesn't result in much improvement in SQ except for a slight improvement in smoothness.  The point here isn't just running AL in memory for the sake of latency but also to be able to completely avoid using an SSD in the server.  The Optane seems to be a nice compromise if capacity, low latency, and low noise are desired since Optane behaves more like RAM than an SSD.  For those with a large Roon database who are looking for a brisk user experience with Roon, an Optane drive may be preferable to a USB stick for the Roon database.  For sure, it would be preferable to an SSD.  From a SQ standpoint, is an Optane drive preferable to having more RAM (16, 32, or even 64GB)?  I'm not sure although according to Intel, a 58GB Optane drive only consumes 3.5w and so it would appear to draw much less current than RAM as a 3.3V device.

 

RAM

 

I haven't done much testing with memory to see what is ideal.  Apparently, Sound Galleries has found that RAM timing matters with respect to SQ but they are keeping mum about what they found to be the ideal RAM timing for their servers.  It made sense to me to target low latency memory and I have had good success as far as compatibility with Kingston's HyperX DDR4 for either Asrock board and for the i7 NUC but I haven't yet played with RAM timing.  As I previously posted, I have not been able to distinguish any difference in sound between 4GB vs 8GB or single channel vs dual channel memory and I believe these findings are supported by the findings of others.  I have been asked about using as much as 64GB of memory in the server.  I have to wonder what the benefits of using large amounts of memory are except for the purposes of a RAM drive to store music since AudioLinux doesn't even occupy 4GB when ramrooted.  According to Crucial, both DDR3 and DDR4 memory consume about 3 watts per 8GB.  That means 16GB consumes 6 watts and 64GB consumes 24 watts.  As 1.2V devices, that represents quite a bit of current draw.  In fact, 24 watts is more than the whole i7 NUC board consumes and while RAM isn't as noisy as an SSD, I have to guess that this amount of consumption is going to result in increased noise in the ground plane.  While storing or caching music files in RAM seems to lead to a slight increase in SQ with AL (a touch more smoothness), I would have to guess that any gains made would likely be offset by the noise created by that much RAM.  I think even 16GB offers no SQ advantage for 2-channel audio, even with OS's that pre-fetch all streaming music into memory (i.e. Euphony).

 

Ethernet - JCAT Femto Network Card

 

I've already provided my experience with optical Ethernet in the SOtM sNH-10G switch and I suspect it would apply to a LAN card one might use in a server also.  With long runs of cable, optical seems to provide an advantage but with short runs, optical has potentially no advantage or actually sounds worse.  This suggests to me that much of the noise that optical is mitigating is coming from the Ethernet cable and not the server and that with short runs of Ethernet cabling or with well-shielded cabling, the higher amounts of jitter that optical creates now becomes its Achilles' heel.  Regardless, even in the best case scenario where optical imparts a benefit (i.e. when compared against a 50+ foot run of Blue Jeans Cables CAT6A), the improvement pales in comparison to what I am hearing with the JCAT Femto Network card.  The JCAT card is a game changer.

 

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I looked at other cards, specifically TLS's LAN card with OCXO but I decided to go with the JCAT card because it had 2 Ethernet ports that I could bridge and because it was the only card I could find that I could independently power with an outboard PSU.  Adrian at TLS told me his network card had redundant linear regulation on board and so bus power should sound as good as an outboard PSU but I refused to believe it.  It just so happens that the JCAT card has the option of either being bus powered or being powered by a 5V outboard PSU and so it was easy to do this comparison.  No surprise, this card when powered by a 5V SR4 sounds incredibly better than bus power.  What did come as a surprise is that the LPS-1.2 is not a good choice for the JCAT card.  To power both Ethernet ports, you need to feed this card at least 1.5A according to Marcin although the LPS-1.2's 1.1A is enough to power one of the Ethernet ports.  The problem here is you not only lose the option of bridging but SQ was just not great because the LPS-1.2 sounds like it's working too hard just to power the one port.  The noise floor is low and articulations are clean and clear but they sound weak and thin.  Even the 5V port from the HDPlex sounds better overall.

 

Not to knock the LPS-1.2 since I regard this PSU very highly and in fact, I own 3 of them but I find that components that draw anywhere close to it's max rating of 1.1A aren't going to sound that great powered by the LPS-1.2.  Also, there are some components that just benefit tremendously from headroom.  A good example is the sNH-10G switch.  The LPS-1.2 powers it fine but it doesn't power it great.  This switch really scales with a 12V DR SR7.  At a minimum, I would suggest an SR4, otherwise, you may feel underwhelmed with this switch.  I imagine the upcoming EtherREGEN will be a better match for the LPS-1.2.

 

Chassis - HDPlex H3 V2 

 

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This proved to be an excellent chassis in many ways for my intended build.  First, it is a fanless chassis capable of dissipating 80w of heat according to HDPlex.  Testing with an i7-8700K running for extended periods at a fixed 4GHz showed that this case could handle that level of CPU just fine.  At no time did CPU temps climb beyond 65 degrees C, however, at that speed and at those temps, harshness was quite evident.  Second, and more importantly, the design of this chassis allowed for the utilization and easy comparison of different outboard ATX power supplies.  The key word here is outboard.  Despite the greater impedance that comes with having to use long umbilical cabling with an outboard PSU, I have found digital components to be very sensitive to vibration and to house a large vibrating transformer in the same chassis as the server is fundamentally against my design philosophy and among the chief reasons I struggle with single-box servers, at least on theoretical grounds.  My former Innuos Zenith SE did a good job isolating the impact of it's large 300VA transformer on the rest of the server but as we know, when it came time to build their no-compromise Statement server, Innuos felt they had to separate the PSU from the main chassis.  If there is a downside to the H3, it's build quality is not to quite to the same level as the fanless cases by Streacom but, nonetheless, it is a solid chassis and nowhere as resonant as many of the Akasas.  Like with all my digital gear, I find that this chassis benefits from good vibration dampening footers as they result in cleaner transients with tighter image focus.

 

One mistake that I did not make with this server that I made with my previous server is the use of EMI paper.  With my previous server build, for those that recall, I lined the whole chassis with EMI paper with the idea that if a little is better, a lot is better still.  Well, I found that too much EMI paper kills the sound and has the potential to sound lifeless and overly damped.  It turns out playing with the harmonic frequencies even at frequencies beyond the audible frequencies (>20kHz) has a very audible effect and so with this build, I have purposely shied away from using EMI paper.  If another used Tranquility Base shows up on Audiogon, that is what I will preferentially target.

 

PSU - HDPlex 400W ATX LPSU

 

I was so impressed by my i7 NUC endpoint with its clocks replaced and powered by a 19V SR7 that I wondered what it would sound like to have the same i7 NUC with the same clocks replaced and powered by a 19V SR7 as the RoonServer.  Well, I tried this and it resulted in an exceptionally clean sound with wonderfully crisp and clear articulations and incredible detail resolution but somehow, compared against the either the 8700T or 8700K, the i7 NUC as a RoonServer lacked soul.  The more powerful machine sounded more dimensional, airier, fuller, more authoritative, and more real.  I went back and forth because each had its appeal but ultimately, the more powerful machine won out as my preferred Roon server.  

 

This led me to wonder how much of what I was hearing was the more powerful CPU vs the PSU.  Was the HDPlex 400W ATX PSU really that good?  I decided to power the i7 NUC with the 19V/10A lead from the HDPlex and even using a custom JSSG360-shielded OFC DC lead made for me by Ghent, compared against the 19V SR7, the HDPlex was a fairly significant step backward.  Noise floor was higher, bass sounded bloated and ill-defined, mids sounded a bit muffled, and treble sounded rolled off.  Not to say the HDPlex sounded horrible (as I previously mentioned, the HDPlex is actually more than just passably good), it's just the 19V SR7 is that much better. 

 

This outcome is a good example of performance being more important than low noise.  When I first described my experience with an unmodified NUC (with AudioLinux) sounding better than a microRendu or sMS-200, people wondered how devices that were built from the ground up for audio playback with high level clocks and low noise regulators could be bested by a cheap NUC.  My only explanation is that low power CPUs like ARM-based processors leave a lot of performance on the table and with Roon Core or RoonServer, I believe this all the more true.  It turns out horsepower isn't beneficial only for upsampling with HQP.  I'm sure this comment will stir a lot of debate and even heated comments but unless someone can propose a better answer, this is what I'm going with.  

 

Some will ask why I didn't go with the 200W HDPlex LPSU when this server consumes no more than about 50 watts max and more typically about 30 watts.  First, I wanted as much headroom as possible.  After speaking with Sean Jacobs, he was very much in favor of over-provisioning any ATX PSU he would design for me to avoid core saturation.  In fact, his design incorporated a 300VA transformer even though I told him I was expecting my server to only consume about 30-35 watts.  Second, I wanted to avoid a DC-ATX converter.  Having purchased and tried the HDPlex 400W DC-ATX converter already back in 2017, I was less than impressed with its performance even when powered by the 19V rail from my SR7.  Sean was also willing to share a few things about what he had learned regarding ATX PSUs (as we know, Sean designed the PSU for both the Zenith SE and the Statement).  According to Sean, the 5V rail is extremely important and requires high current for optimum performance (ideally 4-5A) even if you're not planning on powering any 5V devices such as an SSD.  Apparently, many parts of the motherboard utitilize this rail and unfortunately, the 5V rail on the 200W HDPlex outputs only 2A.  Even if I wished to bypass a DC-ATX converter and create special cables to directly power a motherboard, 2A of output, at least according to Sean, would be less than ideal.

 

As I started doing my listening tests with the HDPlex 400W ATX LPSU, I compared it against a Corsair RM650X ATX PSU.

 

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I specifically chose this 650w Corsair because it had comparatively low ripple noise measurements and very good voltage stability and indeed, before the arrival of the HDPlex, I was quite impressed by its performance.  I wasn't sensing any of the fatiguing harshness I had heard with my Mac Pro or HP workstation.  Against the HDPlex, the Corsair was no match, however.  Noise floor was even lower but the sound signature was also fuller, more dynamic, and harmonically richer.  

 

As I was building servers for others, I had the good fortune of having 2 HDPlex 400W ATX LPSUs on hand and so I got a chance to use both at the same time.  

 

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I used one HDPlex to power the motherboard via the 24-pin ATX connector and the other HDPlex to power the CPU via the 8-pin EPS connector using custom shielded cables made for me by Ghent.  This resulted in further significant improvement -- even better low end dynamics and a more substantial sound stage.  Is it worth another $800 to buy a 2nd HDPlex?  I have to say that it's a very tempting proposition and something worth considering because the difference is there.  Because I had an older 200W HDPlex on hand, I decided a few days ago to try powering the CPU from the 12V lead of this HDPlex using the same custom XLR cable that Ghent made for me and unfortunately, with the 8700K, the 400W HDPlex sounds more dynamic by itself.  I'm sure that a bespoke ATX PSU built by Sean or Adrian would be even better but for $800, I am very impressed with the HDPlex 400W ATX LPSU.  

 

X Factor - Furutech Nano Liquid

 

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This needs to be filed under the "needs to be heard to be believed" catergory.  I received a tip awhile back from a trusted friend to give the Furutech Nano Liquid contact enhancer a try.  Those that know me know that I use a full loom of High Fidelity Cables everywhere except for USB and that's only because High Fidelity Cables don't make USB cables.  Anyway, as good as HFC cables are, I was very impressed by how this Furutech contact enhancer, which is basically a proprietary formulation of silver and gold particles suspended in squalene oil, resulted in an even smoother, richer, and more liquid presentation.  Yes, I know, it wreaks of voodoo but I loved what I was hearing.

 

For my initial server build using the 8700T CPU, I decided to cautiously apply this contact enhancer to the CPU, RAM, Optane card, JCAT card, and the ATX and EPS connectors.  Upon completion of my build, I immediately tried powering on this server but it wouldn't power on.  My first thoughts were that this contact enhancer had somehow caused a short or ruined the board but I decided to wait 24 hours to see what would happen.  To my relief, after 24 hours, the board powered on but the board was only seeing one 4GB RAM stick and not the other.  I switched around the sticks and it became clear that the RAM itself was not the problem but slot 2 on the motherboard was somehow not functioning or at least not detecting RAM that was inserted into this slot.  Was this a defect in the board or a result of the Furutech Nano Liquid?  I'm not sure but I wasn't bummed long because the SQ I got from this server was beyond what I was expecting.  Was it the CPU, the JCAT card, the HDPlex ATX PSU, or the Furutech liquid that was responsible for the magnificent sound?  It was impossible to know for sure.

 

I was asked to build a second server for a friend similar to this first server.  With this second server, I strongly suggested the Asrock gaming ITX motherboard and the i7-8700K.  As I mentioned above, I believed this particular motherboard should, in theory, sound better than the first board because it had more layers in the PCB, more copper in the ground plane, better heat sinking, and a more robust VRM.  Because the 8700K was structurally identical to the 8700T, they should operate similarly but because the 8700K used better binned parts, I reasoned that the 8700K could potentially perform better or at least more durably since I would intentionally be running this CPU well below it's rated peak capability of 4.7GHz.  Not wanting to risk the same headache, I elected not to apply the Furutech Nano Liquid to this build, at least not initially.  The machine powered up fine and with what I thought were appropriate expectations, I was quite let down by what I heard.  It sounded very dynamic but there was a dryness and a harshness to the sound that I wasn't hearing with my other server.  I quickly moved back to my other server and this was immediately confirmed.  My other server sounded smoother, more liquid, and harmonically more pleasing.  

 

Despite 100 hours of burn in, the new server failed to come close to what I was getting with my other server and so I had to let my friend know these findings.  I told him I couldn't say for sure but I didn't think it was the 8700K that was the culprit since I was getting the same temperature readings based on the frequency I was running compared against the 8700T.  I postulated that it had to be either the motherboard that was the culprit or else the Furutech Nano Liquid was the missing X-factor.  I offered him the option of applying the Furutech Nano Liquid but he would have to accept the risk that this liquid could damage his motherboard.  He agreed and so I tore down this machine and started over, this time more copiously applying the Nano Liquid to the CPU, Optane card, RAM, JCAT card, and ATX/EPS connectors.  Since I was given the green light, I figured if we were going to go down and be forced to buy a new motherboard, we might as well go for a home run.  Well, after application of this Furutech liquid, this server did improve...dramatically...and it was noticeable immediately.  If I have to guess, it is with the CPU where this liquid makes the most difference.

 

Operating System - AudioLinux vs Euphony

 

It would be a gross understatement to say that I was merely pleasantly surprised when I first heard a NUC running AudioLinux in RAM and I have Adrian of TLS to thank for this.  What is just as impressive is how open-minded and responsive Piero has been to suggestions and so it has been amazing to see how AudioLinux has evolved in such a short amount of time.  Rajiv and I had asked Piero to allow us the ability to specify CPU frequency and the ability to tune the CPU frequency has been extremely educational.  It also allows for the utilization of just about any CPU since the user is no longer tied to just the base frequency or the peak turbo frequency of a CPU.  Regardless of whether you're using an 8700T, 8700, or 8700K, you can dial in almost any frequency from 400MHz all the way to >4GHz and so with just about any CPU, it becomes a matter of the number of physical cores and the size of the cache.

 

As you go up in frequency, dynamics improves but it is at the expense of subtlety and nuance and at some point, harshness will set in.  I have found that harshness sets in sooner with lower quality PSUs.  With the HDPlex, I can push to 3.8GHz with the 8700T/K before the harshness gets unacceptable.  With the SR7 powering the i7 NUC, I can push as far as the i7-8650U will go (maxes out at 3.8GHz even though Intel claims it can go to 4GHz) and unacceptable harshness never really becomes an issue but this depends on the server CPU frequency.  What is fascinating is that with my large orchestral tracks, I had a preference for running the server at 800MHz which gave me my very best detail while running the NUC endpoint at 3.8GHz which gave the sound more body.  With heavily amplified rock, I found the server sounded best at 3.2GHz and with the NUC endpoint at about 2.2GHz.  It seemed that with the server running at a lower CPU clock speed, the NUC endpoint was receiving a cleaner (less harsh) signal that it could then amplify more agressively without penalty.  With the server running at a higher CPU clock speed, there was more body to the sound but as I advanced the NUC's clock speed, harshness became evident much sooner.  Regardless, to have this level of control has been amazing and I can tell you that these preferred settings apply only to my large listening room with my Wilsons and not to my smaller listening room with the Omegas.  I'm also convinced these settings would be different had I still had my Martin Logans.  

 

This is also the beauty of the core isolation feature and being able to switch between RoonBridge and Squeezelite on the endpoint.  Core isolation in my system results in a tidier and more precise sound signature resulting in tighter focus but at the expense of bloom.  With my Martin Logans, I would have had core isolation tuned on in both the server and the endpoint but with my Wilsons, it sounds too mechanical and so I leave it on in the endpoint but off in the server.  Squeezelite is similar to my ears.  It is a cleaner and more precise presentation whereas RoonBridge can sound more uncontrolled with undersirable overhang but for certain types of music, Squeezelite can sound less natural and overly sterile.  Regardless, I like the option of being able to easily switch between the two.

 

A couple of weeks back, I decided to give Euphony a try at the recommendation of a friend who was impressed with the upgrade from version 2.0 to 3.0.  Euphony lacks the fine manual controls that AudioLinux provides and so this was an immediate red flag for me.  With Euphony, there is no option to set CPU frequency, isolate cores, or bridge LAN ports but it does give the user a polished and easy to use interface.  Where AudioLinux is a tweaker's dream, Euphony was designed for those looking for a more no fuss turnkey solution.  Having spoken by phone with Željko Vranić, one of Euphony's programmers, he said their focus was to lower OS latency as much as possible which really has been Piero's goal at AudioLinux also but it would appear that they have approached latency differently.  Željko told me Euphony makes no attempt to isolate cores or to adjust the CPU frequency since they found this made no difference.  This certainly has not been my experience with AudioLinux.  After comparing the two, at this time, I am getting better SQ with Euphony than AL, especially on the server, and I must say this comes as a surprise, especially since Euphony doesn't allow me to bridge the 2 LAN ports on my JCAT card.  As both products utilize ArchLinux as its platform, I'm confident that AL will continue to evolve and that parity will become possible but thus far, I have been unable to configure AL to match Euphony's performance.  Ultimately, competition is good for the consumer and as I now own both products, I am rooting for both to succeed.

 

I apologize for this War and Peace length post.  It's unlikely you'll see a post like this from me again as I have grown tired of doing comparisons.  Best wishes to all.

Welcome back and Thank you Roy @romaz for another great post with invaluable informations.

 

Let me say to you I love you man and best wishes.

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20 hours ago, Chopin75 said:

Seriously? Can anyone hear that noise when it is loaded ? Would a pause before the start of track help? Though this won’t work if tracks are joined together continuously. Separate LPS on the SSD would help? 

 

 I have no idea whether anyone can hear any such noise.  The thread rules are you can usually not test for it, only post impressions.

 

But if there IS such noise, I offered a more convenient way to reduce it (for those who worry about it).

 

A good SMPS or LPS should help, again if there is an issue.

 

And, of course, if there is not a better way to deal with the putative problem...


"The overwhelming majority [of audiophiles] have very little knowledge, if any, about the most basic principles and operating characteristics of audio equipment. They often base their purchasing decisions on hearsay, and the preaching of media sages. Unfortunately, because of commercial considerations, much information is rooted in increasing revenue, not in assisting the audiophile. It seems as if the only requirements for becoming an "authority" in the world of audio is a keyboard."

-- Bruce Rozenblit of Transcendent Sound

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4 minutes ago, valveboy said:

Or, use a pink faun PCIe/i2s card and forget about USB.

 

Which has got nothing to do with ethernet which was the topic of the post I responded to.

 

Regarding USB vs. I2S..many discussions have taken place about the pros and cons of both..if only it was all so simple and a pure textbook excercise. 🤐

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3 hours ago, romaz said:

It's been a long time and so forgive me if I have a lot to say.  As I indicated in one of my last posts back in 2018, I wouldn't post again unless I felt I had something meaningful to offer.  I have received a lot of inquiries about the status of my audio setup and I apologize as I have not responded to most of these inquiries due to time constraints.  To be honest, since I started this thread back in 2017, my system has been in continual flux but the time has come hopefully to settle down for awhile and so I felt it was finally time to share the status of my setup and to offer some personal observations based on my comparison testing.  This marks my first public post since CA became Audiophile Style.  I miss just being able to say "CA" and having the audiophile community know what I am referring to.

 

As always, what I have to share are personal observations and opinions based on my sensitivities and personal preferences.  I have no financial motivations.  I have 2 systems at home and what works well in one system doesn't always work well in the other.  In other words, YMMV.

 

As for my 2 systems, they are as follows:

 

In my home office, I have a pair of near field desktop monitors that were custom made for me by Louis Chochos of Omega Speaker Systems based in Connecticut.  They cost me <$2k and they remain one of the highest value purchases I have ever made.  They are comprised of Louis' high efficiency, crossover-less Alnico drivers and excel in delicacy, nuance, and tone.  I am continually amazed by how well these drivers express the subtlest textures.  I used to own a pair of custom made Voxativs that were even more resolving and oh so velvety smooth but also a tad bright and not ideally suited for long term near field listening and so those are now gone.  Paired with a fast JL Audio Fathom F110 V2 subwoofer and driven directly by a Chord Hugo TT2 / Hugo M-Scaler, I find this Omega setup to be very transparent, highly resolving, non-fatiguing, and transfixing.  I own or have owned many fine headphones over the years (SR-009, HD800/HD800S, HE-1000 V2, Abyss 1266, LCD-4, Focal Utopia, Dharma D1000, TH-900) and when my children were living at home before they moved off to college, I found myself forced to headphone listening at night but my headphones have been collecting dust for some time because I have found my Chord DAC directly driving these Omegas to be that much more engaging, even at low listening volumes. 

 

With my youngest son having moved out of the house and onto college late last year, my big listening room is where I do most of my listening these days.  This room has been home to a lot of different speakers over the years and for most of the previous year, I was using a pair of large Martin Logan Renaissance 15A hybrid electrostats.  Typical of line source, dipole speakers, these Martin Logans cast a giant ambient sound stage and are wonderful for recreating large venue performances at full scale.  Driven by a Pass Labs X350.8 amp and XP-22 preamp, this setup excelled in beauty but ultimately lacked in resolution and transparency even when fronted by my Chord DAVE DAC with M-Scaler.  These giant electrostat panels, while very fast and with exceptional clarity, created a softly focused image and so point sources like a solo cello or a solo vocalist sounded too diffuse, too tall, and too wide for my tastes, regardless of speaker position.  As I made tweaks in my upstream setup, I could hear changes, however, I could hear these changes much more succinctly with my inexpensive Omegas and so for someone who values transparency, this drove me nuts.  Imaging and focus improved considerably with a switch from Pass Labs amplification to a more resolving Luxman M-900U/C900U and ultimately to Soulution amplification.  Imaging and focus further improved dramatically when I moved from a Shunyata Triton V3 to a Sound Application TT-7 line conditioner by Jim Weil but despite these improvements, I eventually came to the realization that I was not meant for line source speakers like electrostats or planars like my brother's Maggies.  Don't get me wrong, these are wonderful types of speakers with tremendous appeal but my time with the Martin Logans have better educated me as to the type of listening I prefer and so I have moved on to point source speakers once again in my large listening room, specifically the Wilson Alexia 2s.

 

I offer the above details for the following reason.  It's important to understand the context by which my observations and opinions are based and the priorities that I value as your priorities may be different.  I'm guessing that we all claim live music as our reference and yet it's interesting to see how we each vary in our approach to achieving the recreation of a live performance.  Because today's technologies remain incapable of faithfully reproducing a live musical performance and because we each are constrained by a budget, it helps to know what type of listener you are to understand which compromises you should accept above others.  My goals, simply stated, are resolution and transparency in the absence of harshness.  I aspire to beauty, organic, natural, and musical just like everyone else but these qualities are more in the eye (or ear) of the beholder and are not easy to define.  I tend to run from things that are described as warm (meaning slow), thick, heavy, euphonic, or lush.  Not that I don't like warm or lush, I just don't want everything sounding warm and lush if warm and lush aren't in the recording.  Just not me.  I find that if you can successfully address harshness at every step in your chain, there's usually no need to embellish or to colorize.

 

Moving on, here's a story about listening that some will find interesting.  There are 2 types of listening that most of us do.  There is critical listening where we focus on what we are hearing hoping to dissect the qualities of a performance, recording, or some piece of equipment and then there is pleasurable listening where the goal is to relax and to escape.  Given the choice, I'm sure most of us would prefer the latter.  Almost a year ago to this day, I hosted Rob Watts (who needs no introduction), Jay Luong (lead reviewer for AudioBacon.net), and Jim Weil (owner of Sound Application and designer of SA's line conditioners) in my home for a series of listening tests.  What I respect about these 3 gentlemen is that they are each highly educated and accomplished electrical engineers but also passionate music lovers.  It has been my experience that most engineers aren't true music lovers, don't know how to critically listen, or worse, they're closed-minded with fixed ideas about how digital electronics are supposed to sound based on theory alone.  Not these gentlemen.  

 

Rob had come all the way from Wales and brought along prototypes of M-Scaler and Hugo TT2 for us to listen to and for the better part of 5 days, we conducted a series of critical listening tests.  We did a lot of listening, both sighted and blinded, to Rob's prototypes, to different DACs, amps, cables, line conditioners, and speakers.  While it was a lot of fun to hang out with these individuals, our listening sessions were often more tedious than enjoyable.  We listened to select portions of Mahler's 1st symphony so many times that I couldn't listen to this symphony again for months.  What I found fascinating but not surprising is that while we each heard differences, we heard them differently and had different preferences.  Jim Weil had a strong aversion to anything bright.  Rhodium and silver-plated copper are Jim's enemies and he could sniff them from a mile away.  Jay Luong was especially sensitive to tone and timbre and would gladly trade detail for warmth.  Rob was particular to depth.  An organ that was 30 feet away had to sound as if it was 30 feet away.  Everything else was secondary and so not surprisingly, his DACs excel in depth accuracy.  My sensitivities are more toward transient response and the air and space around voices and instruments.  I also crave variation over harmony.  Even 2 Stradivariuses should never sound exactly the same and a system that makes them sound exactly the same simply isn't transparent enough.  We are who we are and so gear will speak differently to each of us.

 

Single box server vs server + endpoint

 

There are compelling examples to support either strategy.  In the perfect world, I would love to have the convenience of a single box solution but I have yet to hear a single box solution that I prefer over a multiple box solution.  With multiple boxes, there is the option for finer level tuning which I will discuss further but ultimately, it comes down to how well each box can be powered.  If all I can come up with is a single good PSU, than a single box server is all that I will aspire to.

 

The Endpoint

 

Those who have followed this thread from the beginning know that its original goal was to figure out ways to improve endpoints like the sMS-200 or microRendu.  It's amazing how endpoints have evolved since January 1, 2017.  The concept behind the endpoint was to create a low noise rendering device to interface with the DAC that isolates against noise generated by a powerful computer server.  Low noise was the rationale for using low power processors like ARM-based CPUs and even Celerons.  It was also the premise behind the avoidance of other noisy components like SSDs and switching power supplies.  While some of these principles have passed the test of time, others have not, at least not to my ears.  Low power CPUs are not necessarily what sound best.  How else can I explain how an i7 NUC board with its noisy switching regulators can sound better than an ARM-based sMS-200ultra or ultraRendu?  How else can I explain how an i7 NUC can sound better as I ramp up CPU clock frequency?  It's completely counter-intuitive but it suggests that aside from noise, there is performance to consider and sometimes performance requires power and sometimes performance is more important than low noise.  To my ears, an i7 has the potential to sound more spacious, fuller, and more dynamic than a Celeron or ARM-based CPU and the number of physical cores, CPU frequency and size of the CPU cache seem to matter.  The downside of the i7 is that they are potentially more challenging to power well.

 

Thus far, I have tested 5 NUC boards comprised of either a Celeron, i5, or i7 CPU and ranging from 2-cores to 4-cores and from 2MB of standard CPU cache to 8MB of SmartCache.  The best sounding board I have heard thus far is the NUC7i7DNBE based on an 8th generation i7 that I first discussed a few months ago.  

 

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I am open to the idea that a more powerful, non-NUC device could sound even better as an endpoint but once again, powering it would be the challenge.  Here is the Asrock IMB-1215 which will be released to the U.S. in a few months.  

 

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It is a mini-ITX board that can accommodate an 8th or 9th generation i7 and with an open PCIe slot that can be powered by a single 19V rail and so I find this board to have intriguing possibilities.


SOtM has reportedly designed an i7-based motherboard from the ground up with high level clocks that can be powered by a single 19V PSU.  I very much look forward to trying out this board.  

 

The NUC7i7DNBE when purchased as a board are more difficult to come by and also more expensive at a price of around $650 USD.  Ironically, the NUC7i7DNKE NUC kit, which houses a NUC7i7DNBE board within a standard Intel chassis are much more readily available and cost $100 less.  I just purchased one a few weeks ago and it took all of 5 minutes to explant the NUC7i7DNBE board from the chassis.

 

The NUC7i7DNBE has the option of being powered by a 12-24V PSU and higher voltage DEFINITELY sounds better to me.  Bigger and more dynamic.  It also has the option of being powered via either a 2.5mm x 5.5mm barrel connector or 2x2 mini Molex connector.  With 2 NUC7i7DNBE boards on hand, I was able to recently do a direct A/B and powering via the 2x2 Molex connector sounds very slightly better.  

 

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As for power supplies, I could not successfully power a NUC7i7DNBE board with a single LPS-1.2 at 12V even though my Kill-a-Watt meter suggests this board never consumes more than 8 watts during bootup.  I could get it to post to the BIOS screen but even with Turbo and Hyperthreading turned off and with only 4GB of RAM installed, I could not successfully boot into AudioLinux from a USB stick.  I purchased a special serial Y-cable from Ghent Audio and this allowed me to combine two LPS-1.2s and this worked.  The cable that I had Ghent make for me is comprised of high quality Neotech 18g 7N OCC copper and so I spared no expense to get it as I was very excited by the prospect of being able to power the NUC with 24V using two LPS-1.2s set at 12V each.  

 

Unfortunately, for reasons that remain a mystery, I could not get this to work.  Each time, one of the LPS-1.2s would start to blink red during the boot process and turn very hot.  I own three LPS-1.2s and regardless of which one I swapped in, one of the LPS-1.2s would start to blink red and it was not always the same LPS-1.2 that would give out.  When I kept one LPS-1.2 at 12V and switched the other to 9V (12V + 9V = 21V), this somehow worked and the NUC booted just fine.  19V (12V + 7V) also worked.  The problem with using two LPS-1.2s in serial is that they don't sound good at all and this was very disappointing.  In fact, I found better SQ powering the NUC with the 19V rail from my HDPlex which came as a surprise.  It appears that using 2 or more LPS-1.2s in serial is not a good thing to do.  The NUCi7DNBE also likes headroom and the LPS-1.2's 1.1A of headroom is a limitation.  To hightlight the importance of headroom further, a 12V SR4 sounds very good powering this NUC but a 12V SR7 with its greater headroom sounds even better.  

 

Beyond headroom, the avoidance of any voltage drop is also very important and a 12V DR (double regulated) SR7 sounds better yet although I am getting my very best SQ with this NUC powered by a 19V SR SR7 rail.  With this NUC powered by the 19V rail from an HDPlex 400W ATX LPSU, while the SQ is not in the same league as an SR7 or even the SR4, it is much less harsh than the stock 19V switcher that Intel provides and so the HDPlex is more than just a passable option.  The JS-2 or a bespoke PSU from either Sean Jacobs or Adrian Wun at TLS could be even better options but at a cost.  As I stated above, the downside of the i7 is that they are potentially more challenging to power well but I do feel the rewards are there.

 

As for clocking, not surprisingly, this makes a significant and worthwhile difference.  I had the TLS DS-1 on hand for a few months and it's single OCXO reportely replaced 3 clocks on this board (system, Ethernet, USB).  

 

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While much has been made about the mediocre performance characteristics of the Connor-Winfield OCXO that Adrian at TLS likes to use for all of his products, the removal of 3 noisily powered clocks from this board and replacing it with a cleanly powered clock even if that clock is of suspect performance has paid significant dividends.  I had a stock NUC7JYH board with its Celeron J4005 CPU on hand and it is the very same board and CPU that Adrian used for the DS-1.  Direct A/B revealed a significant uptick in detail clarity and spaciousness with the DS-1.  Compared against my stock NUC7i7DNBE, this superior detail clarity was still very much evident although I found the i7 NUC to sound more spacious still.  Regardless, I heard enough to know that it would be worthwhile to send my i7 board to SOtM for clock replacement and indeed, it has been worthwhile.  To have replaced the 4 replaceable clocks on this board has resulted in a notable decrease in harshness resulting in cleaner transients, better definition, more accurate timbre, and a greater sense of space.

 

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However, the benefits of clocking have to be placed in proper perspective.  To my ears, the power supply still makes the bigger difference.  I have the benefit of having 2 NUC7i7DNBE boards on hand (one is stock and the other has been reclocked) and this has allowed me to make careful A/B comparisons.  With the stock i7 NUC powered by a 19V rail from my SR7, I am getting better SQ overall than the SOtM-modified NUC powered by the 19V rail from the 400W HDPlex.  If forced to choose, the choice would be easy.

 

The Server

 

With my inaugural post on this thread, I had described my observations about how LAN bridging resulted in increased transparency of the endpoint to the upstream server.  While the mechanism for why this improves transparency remains unsettled, with bridging, it was clear to me that the quality of the server mattered.  With the release of the SOtM sNH-10G switch last year, I reported that I was no longer able to differentiate between the Zenith SE and my noisy 12-core Xeon-based Mac Pro when either one was used as a Roon server.  But that was before AudioLinux came into the picture which allowed me to play with CPU frequency settings and this has made all the difference.  The Zenith SE houses a powerful and low noise PSU but it is mated to a very weak Celeron while my Mac Pro utilizes a noisy switching PSU mated to a much more capable 12-core Xeon with a giant CPU cache.  Without any OS manipulation of the CPU, cursory A/B comparisons between the two yielded no significant difference to my ears suggesting that the sNH-10G had effectively blocked the higher noise that was being generated by my Mac Pro.

 

But what would happen if I pushed my Mac Pro's CPU clock from it's base idle frequency to max turbo levels?  Of course, this is the beauty of AudioLinux and it has proven to be a very useful learning tool.  With higher CPU frequency, dynamics goes up but at the expense of subtlety and nuance and with progressively increasing harshness and the sNH-10G is incapable of completely isolating against these changes.  I have read commentary that the upcoming opticalRendu will supposedly be completely immune to the virtues of the upstream server.  I suspect this is probably the goal of the upcoming EtherREGEN also.  Well, I believe this is both naive and wishful thinking and so people will need to adjust their expectations appropriately or else they will be disappointed.  

 

I say this because I currently have 2 SOtM sNH-10G switches in my possession and I can tell you that while 1 switch makes a very big difference, 2 switches make an even bigger difference.

 

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What is nice about these switches is that they have both standard RJ-45 Ethernet ports as well as optical Ethernet ports and so with these switches connected by a single-mode fiber optic cable, here is what I found.

 

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With the optical cable compared against a 50+ foot Blue Jeans Cables CAT6A Ethernet cable, the noise floor with the optical cable was noticeably lower and there is a clear preference for the optical connection.  With the optical cable compared against a 22-foot Belden CAT6A cable with JSSG360 shielding that was made for me by Ghent, the gap was smaller but there was still a slight preference for the optical cable.  With the optical cable compared against a heavily shielded 1.5m SOtM dCBL-CAT7 cable, the noise floor was equivalent (at least to my ears) but tonality with the SOtM cable sounded more natural.  The optical cable sounded a touch thin and bright in comparison and so in this instance, the copper Ethernet cable sounded better.  Regardless, in each and every comparison, optical or otherwise, if I varied CPU frequency, I could hear differences in the server.  The server still ABSOLUTELY matters and this is because it's not just about noise, there is also the matter of performance and it would appear that RoonServer likes horsepower.  At this time, the delta I am hearing from my best server setup to my worst server setup is about the same as the delta I am hearing from by best endpoint setup to my worst.  In other words, my current stand is that the server matters as much as the endpoint.

 

CPU

 

My testing has shown me that modern CPUs are preferable to older generation CPUs  A few generations ago, an i7-4790 yielded a TDP of 84w with 4-cores/8-threads, 8MB of SmartCache and CPU turbo speeds reaching 4GHz.  Today, an i7-8700T yields a TDP of only 35w but offers 6-cores/12-threads, 12MB of SmartCache and CPU turbo speeds reaching the same 4.0GHz.  Basically, more performance with less noise and A/B comparisons between these 2 CPUs reveal exactly that.  An 8700K houses potentially even greater performance with a max turbo rating of 4.7GHz using better binned parts according to Intel and so I decided to compare this against the 8700T.  

 

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Ultimately, it didn't seem to matter since I heard no benefit clocking either of these CPU beyond 3.8GHz when powered by the HDPlex 400W ATX LPSU due to harshness but who knows what would happen if I had a better ATX PSU on hand?  I have explored such a PSU with both Adrian Wun of TLS and Sean Jacobs but the cost of a "no compromise" ATX PSU from these gentlemen will run somewhere in the $4-5k range. Regardless, the CPU matters and if I were to build another server, I would probably go for a standard i7-8700 since they're more readily available and less expensive then either the 8700T or 8700K.

 

Motherboards

 

My testing has shown me that the motherboard matters also.  Borrowing a page from Pink Faun's book that gaming boards can sound better, I decided to compare a standard Asrock Z370M-ITX/ac motherboard against an Asrock Z390 Phantom Gaming-ITX/ac motherboard.  

 

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First of all, I only looked at Intel boards since it wasn't clear to me that an AMD board was compatible with Optane memory.  Second, I specifically targeted the Z370/390 chipset because these chipsets were capable of running the latest generation i7s (both 8th and 9th gen).  The Z390 board happened to be designed for gaming meaning they were engineered to be overclocked.  As such, this gaming board has an 8-layer PCB with a whopping 8oz of copper to maximize conductivity and to enhance the ground plane.  This board also has beefier heat sinks to improve heat dissipation and a more robust VRM (voltate regulator module) to make sure the CPU is never starved of current.  While the differences weren't large, the gaming board had more substance to the sound stage with greater authority to its presentation but not to be completely outdone, the Z370 board had a touch better finesse and subtlety.  The point is that even these more minor differences were easily audible in the server.

 

SSD vs Optane

 

Just for kicks, I decided to compare a 58GB Optane card against a Samsung 500GB 960 EVO NVMe SSD in the M.2 slot of the Asrock board.  This was a very brief comparison because it didn't take long to realize how much more harsh the SSD sounded even with all of my isolation schemes in place.  It's amazing how many commercial music server manufacturers continue to use SSD drives in their servers as if powering an SSD cleanly somehow addresses this harshness when it does not, at least not to my ears.  I suppose you get used to the harshness over time but an SSD is about the worst thing I can imagine putting into a music server with the super fast NVMe drives sounding the harshest of all.  As some may recall, in previous testing, I found the older, slower SATA II SSDs (especially the SLC variety) to sound less harsh then the newer, faster SATA III SSDs although the faster SATA III SSDs made music sound more alive and more immediate and so there was a trade off.  It would appear that the Optane cards have the best of both worlds and so hats off to Larry for introducing us to the Optanes.

 

I have read comments about how running AL in memory doesn't result in much improvement in SQ except for a slight improvement in smoothness.  The point here isn't just running AL in memory for the sake of latency but also to be able to completely avoid using an SSD in the server.  The Optane seems to be a nice compromise if capacity, low latency, and low noise are desired since Optane behaves more like RAM than an SSD.  For those with a large Roon database who are looking for a brisk user experience with Roon, an Optane drive may be preferable to a USB stick for the Roon database.  For sure, it would be preferable to an SSD.  From a SQ standpoint, is an Optane drive preferable to having more RAM (16, 32, or even 64GB)?  I'm not sure although according to Intel, a 58GB Optane drive only consumes 3.5w and so it would appear to draw much less current than RAM as a 3.3V device.

 

RAM

 

I haven't done much testing with memory to see what is ideal.  Apparently, Sound Galleries has found that RAM timing matters with respect to SQ but they are keeping mum about what they found to be the ideal RAM timing for their servers.  It made sense to me to target low latency memory and I have had good success as far as compatibility with Kingston's HyperX DDR4 for either Asrock board and for the i7 NUC but I haven't yet played with RAM timing.  As I previously posted, I have not been able to distinguish any difference in sound between 4GB vs 8GB or single channel vs dual channel memory and I believe these findings are supported by the findings of others.  I have been asked about using as much as 64GB of memory in the server.  I have to wonder what the benefits of using large amounts of memory are except for the purposes of a RAM drive to store music since AudioLinux doesn't even occupy 4GB when ramrooted.  According to Crucial, both DDR3 and DDR4 memory consume about 3 watts per 8GB.  That means 16GB consumes 6 watts and 64GB consumes 24 watts.  As 1.2V devices, that represents quite a bit of current draw.  In fact, 24 watts is more than the whole i7 NUC board consumes and while RAM isn't as noisy as an SSD, I have to guess that this amount of consumption is going to result in increased noise in the ground plane.  While storing or caching music files in RAM seems to lead to a slight increase in SQ with AL (a touch more smoothness), I would have to guess that any gains made would likely be offset by the noise created by that much RAM.  I think even 16GB offers no SQ advantage for 2-channel audio, even with OS's that pre-fetch all streaming music into memory (i.e. Euphony).

 

Ethernet - JCAT Femto Network Card

 

I've already provided my experience with optical Ethernet in the SOtM sNH-10G switch and I suspect it would apply to a LAN card one might use in a server also.  With long runs of cable, optical seems to provide an advantage but with short runs, optical has potentially no advantage or actually sounds worse.  This suggests to me that much of the noise that optical is mitigating is coming from the Ethernet cable and not the server and that with short runs of Ethernet cabling or with well-shielded cabling, the higher amounts of jitter that optical creates now becomes its Achilles' heel.  Regardless, even in the best case scenario where optical imparts a benefit (i.e. when compared against a 50+ foot run of Blue Jeans Cables CAT6A), the improvement pales in comparison to what I am hearing with the JCAT Femto Network card.  The JCAT card is a game changer.

 

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I looked at other cards, specifically TLS's LAN card with OCXO but I decided to go with the JCAT card because it had 2 Ethernet ports that I could bridge and because it was the only card I could find that I could independently power with an outboard PSU.  Adrian at TLS told me his network card had redundant linear regulation on board and so bus power should sound as good as an outboard PSU but I refused to believe it.  It just so happens that the JCAT card has the option of either being bus powered or being powered by a 5V outboard PSU and so it was easy to do this comparison.  No surprise, this card when powered by a 5V SR4 sounds incredibly better than bus power.  What did come as a surprise is that the LPS-1.2 is not a good choice for the JCAT card.  To power both Ethernet ports, you need to feed this card at least 1.5A according to Marcin although the LPS-1.2's 1.1A is enough to power one of the Ethernet ports.  The problem here is you not only lose the option of bridging but SQ was just not great because the LPS-1.2 sounds like it's working too hard just to power the one port.  The noise floor is low and articulations are clean and clear but they sound weak and thin.  Even the 5V port from the HDPlex sounds better overall.

 

Not to knock the LPS-1.2 since I regard this PSU very highly and in fact, I own 3 of them but I find that components that draw anywhere close to it's max rating of 1.1A aren't going to sound that great powered by the LPS-1.2.  Also, there are some components that just benefit tremendously from headroom.  A good example is the sNH-10G switch.  The LPS-1.2 powers it fine but it doesn't power it great.  This switch really scales with a 12V DR SR7.  At a minimum, I would suggest an SR4, otherwise, you may feel underwhelmed with this switch.  I imagine the upcoming EtherREGEN will be a better match for the LPS-1.2.

 

Chassis - HDPlex H3 V2 

 

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This proved to be an excellent chassis in many ways for my intended build.  First, it is a fanless chassis capable of dissipating 80w of heat according to HDPlex.  Testing with an i7-8700K running for extended periods at a fixed 4GHz showed that this case could handle that level of CPU just fine.  At no time did CPU temps climb beyond 65 degrees C, however, at that speed and at those temps, harshness was quite evident.  Second, and more importantly, the design of this chassis allowed for the utilization and easy comparison of different outboard ATX power supplies.  The key word here is outboard.  Despite the greater impedance that comes with having to use long umbilical cabling with an outboard PSU, I have found digital components to be very sensitive to vibration and to house a large vibrating transformer in the same chassis as the server is fundamentally against my design philosophy and among the chief reasons I struggle with single-box servers, at least on theoretical grounds.  My former Innuos Zenith SE did a good job isolating the impact of it's large 300VA transformer on the rest of the server but as we know, when it came time to build their no-compromise Statement server, Innuos felt they had to separate the PSU from the main chassis.  If there is a downside to the H3, it's build quality is not to quite to the same level as the fanless cases by Streacom but, nonetheless, it is a solid chassis and nowhere as resonant as many of the Akasas.  Like with all my digital gear, I find that this chassis benefits from good vibration dampening footers as they result in cleaner transients with tighter image focus.

 

One mistake that I did not make with this server that I made with my previous server is the use of EMI paper.  With my previous server build, for those that recall, I lined the whole chassis with EMI paper with the idea that if a little is better, a lot is better still.  Well, I found that too much EMI paper kills the sound and has the potential to sound lifeless and overly damped.  It turns out playing with the harmonic frequencies even at frequencies beyond the audible frequencies (>20kHz) has a very audible effect and so with this build, I have purposely shied away from using EMI paper.  If another used Tranquility Base shows up on Audiogon, that is what I will preferentially target.

 

PSU - HDPlex 400W ATX LPSU

 

I was so impressed by my i7 NUC endpoint with its clocks replaced and powered by a 19V SR7 that I wondered what it would sound like to have the same i7 NUC with the same clocks replaced and powered by a 19V SR7 as the RoonServer.  Well, I tried this and it resulted in an exceptionally clean sound with wonderfully crisp and clear articulations and incredible detail resolution but somehow, compared against the either the 8700T or 8700K, the i7 NUC as a RoonServer lacked soul.  The more powerful machine sounded more dimensional, airier, fuller, more authoritative, and more real.  I went back and forth because each had its appeal but ultimately, the more powerful machine won out as my preferred Roon server.  

 

This led me to wonder how much of what I was hearing was the more powerful CPU vs the PSU.  Was the HDPlex 400W ATX PSU really that good?  I decided to power the i7 NUC with the 19V/10A lead from the HDPlex and even using a custom JSSG360-shielded OFC DC lead made for me by Ghent, compared against the 19V SR7, the HDPlex was a fairly significant step backward.  Noise floor was higher, bass sounded bloated and ill-defined, mids sounded a bit muffled, and treble sounded rolled off.  Not to say the HDPlex sounded horrible (as I previously mentioned, the HDPlex is actually more than just passably good), it's just the 19V SR7 is that much better. 

 

This outcome is a good example of performance being more important than low noise.  When I first described my experience with an unmodified NUC (with AudioLinux) sounding better than a microRendu or sMS-200, people wondered how devices that were built from the ground up for audio playback with high level clocks and low noise regulators could be bested by a cheap NUC.  My only explanation is that low power CPUs like ARM-based processors leave a lot of performance on the table and with Roon Core or RoonServer, I believe this all the more true.  It turns out horsepower isn't beneficial only for upsampling with HQP.  I'm sure this comment will stir a lot of debate and even heated comments but unless someone can propose a better answer, this is what I'm going with.  

 

Some will ask why I didn't go with the 200W HDPlex LPSU when this server consumes no more than about 50 watts max and more typically about 30 watts.  First, I wanted as much headroom as possible.  After speaking with Sean Jacobs, he was very much in favor of over-provisioning any ATX PSU he would design for me to avoid core saturation.  In fact, his design incorporated a 300VA transformer even though I told him I was expecting my server to only consume about 30-35 watts.  Second, I wanted to avoid a DC-ATX converter.  Having purchased and tried the HDPlex 400W DC-ATX converter already back in 2017, I was less than impressed with its performance even when powered by the 19V rail from my SR7.  Sean was also willing to share a few things about what he had learned regarding ATX PSUs (as we know, Sean designed the PSU for both the Zenith SE and the Statement).  According to Sean, the 5V rail is extremely important and requires high current for optimum performance (ideally 4-5A) even if you're not planning on powering any 5V devices such as an SSD.  Apparently, many parts of the motherboard utitilize this rail and unfortunately, the 5V rail on the 200W HDPlex outputs only 2A.  Even if I wished to bypass a DC-ATX converter and create special cables to directly power a motherboard, 2A of output, at least according to Sean, would be less than ideal.

 

As I started doing my listening tests with the HDPlex 400W ATX LPSU, I compared it against a Corsair RM650X ATX PSU.

 

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I specifically chose this 650w Corsair because it had comparatively low ripple noise measurements and very good voltage stability and indeed, before the arrival of the HDPlex, I was quite impressed by its performance.  I wasn't sensing any of the fatiguing harshness I had heard with my Mac Pro or HP workstation.  Against the HDPlex, the Corsair was no match, however.  Noise floor was even lower but the sound signature was also fuller, more dynamic, and harmonically richer.  

 

As I was building servers for others, I had the good fortune of having 2 HDPlex 400W ATX LPSUs on hand and so I got a chance to use both at the same time.  

 

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I used one HDPlex to power the motherboard via the 24-pin ATX connector and the other HDPlex to power the CPU via the 8-pin EPS connector using custom shielded cables made for me by Ghent.  This resulted in further significant improvement -- even better low end dynamics and a more substantial sound stage.  Is it worth another $800 to buy a 2nd HDPlex?  I have to say that it's a very tempting proposition and something worth considering because the difference is there.  Because I had an older 200W HDPlex on hand, I decided a few days ago to try powering the CPU from the 12V lead of this HDPlex using the same custom XLR cable that Ghent made for me and unfortunately, with the 8700K, the 400W HDPlex sounds more dynamic by itself.  I'm sure that a bespoke ATX PSU built by Sean or Adrian would be even better but for $800, I am very impressed with the HDPlex 400W ATX LPSU.  

 

X Factor - Furutech Nano Liquid

 

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This needs to be filed under the "needs to be heard to be believed" catergory.  I received a tip awhile back from a trusted friend to give the Furutech Nano Liquid contact enhancer a try.  Those that know me know that I use a full loom of High Fidelity Cables everywhere except for USB and that's only because High Fidelity Cables don't make USB cables.  Anyway, as good as HFC cables are, I was very impressed by how this Furutech contact enhancer, which is basically a proprietary formulation of silver and gold particles suspended in squalene oil, resulted in an even smoother, richer, and more liquid presentation.  Yes, I know, it wreaks of voodoo but I loved what I was hearing.

 

For my initial server build using the 8700T CPU, I decided to cautiously apply this contact enhancer to the CPU, RAM, Optane card, JCAT card, and the ATX and EPS connectors.  Upon completion of my build, I immediately tried powering on this server but it wouldn't power on.  My first thoughts were that this contact enhancer had somehow caused a short or ruined the board but I decided to wait 24 hours to see what would happen.  To my relief, after 24 hours, the board powered on but the board was only seeing one 4GB RAM stick and not the other.  I switched around the sticks and it became clear that the RAM itself was not the problem but slot 2 on the motherboard was somehow not functioning or at least not detecting RAM that was inserted into this slot.  Was this a defect in the board or a result of the Furutech Nano Liquid?  I'm not sure but I wasn't bummed long because the SQ I got from this server was beyond what I was expecting.  Was it the CPU, the JCAT card, the HDPlex ATX PSU, or the Furutech liquid that was responsible for the magnificent sound?  It was impossible to know for sure.

 

I was asked to build a second server for a friend similar to this first server.  With this second server, I strongly suggested the Asrock gaming ITX motherboard and the i7-8700K.  As I mentioned above, I believed this particular motherboard should, in theory, sound better than the first board because it had more layers in the PCB, more copper in the ground plane, better heat sinking, and a more robust VRM.  Because the 8700K was structurally identical to the 8700T, they should operate similarly but because the 8700K used better binned parts, I reasoned that the 8700K could potentially perform better or at least more durably since I would intentionally be running this CPU well below it's rated peak capability of 4.7GHz.  Not wanting to risk the same headache, I elected not to apply the Furutech Nano Liquid to this build, at least not initially.  The machine powered up fine and with what I thought were appropriate expectations, I was quite let down by what I heard.  It sounded very dynamic but there was a dryness and a harshness to the sound that I wasn't hearing with my other server.  I quickly moved back to my other server and this was immediately confirmed.  My other server sounded smoother, more liquid, and harmonically more pleasing.  

 

Despite 100 hours of burn in, the new server failed to come close to what I was getting with my other server and so I had to let my friend know these findings.  I told him I couldn't say for sure but I didn't think it was the 8700K that was the culprit since I was getting the same temperature readings based on the frequency I was running compared against the 8700T.  I postulated that it had to be either the motherboard that was the culprit or else the Furutech Nano Liquid was the missing X-factor.  I offered him the option of applying the Furutech Nano Liquid but he would have to accept the risk that this liquid could damage his motherboard.  He agreed and so I tore down this machine and started over, this time more copiously applying the Nano Liquid to the CPU, Optane card, RAM, JCAT card, and ATX/EPS connectors.  Since I was given the green light, I figured if we were going to go down and be forced to buy a new motherboard, we might as well go for a home run.  Well, after application of this Furutech liquid, this server did improve...dramatically...and it was noticeable immediately.  If I have to guess, it is with the CPU where this liquid makes the most difference.

 

Operating System - AudioLinux vs Euphony

 

It would be a gross understatement to say that I was merely pleasantly surprised when I first heard a NUC running AudioLinux in RAM and I have Adrian of TLS to thank for this.  What is just as impressive is how open-minded and responsive Piero has been to suggestions and so it has been amazing to see how AudioLinux has evolved in such a short amount of time.  Rajiv and I had asked Piero to allow us the ability to specify CPU frequency and the ability to tune the CPU frequency has been extremely educational.  It also allows for the utilization of just about any CPU since the user is no longer tied to just the base frequency or the peak turbo frequency of a CPU.  Regardless of whether you're using an 8700T, 8700, or 8700K, you can dial in almost any frequency from 400MHz all the way to >4GHz and so with just about any CPU, it becomes a matter of the number of physical cores and the size of the cache.

 

As you go up in frequency, dynamics improves but it is at the expense of subtlety and nuance and at some point, harshness will set in.  I have found that harshness sets in sooner with lower quality PSUs.  With the HDPlex, I can push to 3.8GHz with the 8700T/K before the harshness gets unacceptable.  With the SR7 powering the i7 NUC, I can push as far as the i7-8650U will go (maxes out at 3.8GHz even though Intel claims it can go to 4GHz) and unacceptable harshness never really becomes an issue but this depends on the server CPU frequency.  What is fascinating is that with my large orchestral tracks, I had a preference for running the server at 800MHz which gave me my very best detail while running the NUC endpoint at 3.8GHz which gave the sound more body.  With heavily amplified rock, I found the server sounded best at 3.2GHz and with the NUC endpoint at about 2.2GHz.  It seemed that with the server running at a lower CPU clock speed, the NUC endpoint was receiving a cleaner (less harsh) signal that it could then amplify more agressively without penalty.  With the server running at a higher CPU clock speed, there was more body to the sound but as I advanced the NUC's clock speed, harshness became evident much sooner.  Regardless, to have this level of control has been amazing and I can tell you that these preferred settings apply only to my large listening room with my Wilsons and not to my smaller listening room with the Omegas.  I'm also convinced these settings would be different had I still had my Martin Logans.  

 

This is also the beauty of the core isolation feature and being able to switch between RoonBridge and Squeezelite on the endpoint.  Core isolation in my system results in a tidier and more precise sound signature resulting in tighter focus but at the expense of bloom.  With my Martin Logans, I would have had core isolation tuned on in both the server and the endpoint but with my Wilsons, it sounds too mechanical and so I leave it on in the endpoint but off in the server.  Squeezelite is similar to my ears.  It is a cleaner and more precise presentation whereas RoonBridge can sound more uncontrolled with undersirable overhang but for certain types of music, Squeezelite can sound less natural and overly sterile.  Regardless, I like the option of being able to easily switch between the two.

 

A couple of weeks back, I decided to give Euphony a try at the recommendation of a friend who was impressed with the upgrade from version 2.0 to 3.0.  Euphony lacks the fine manual controls that AudioLinux provides and so this was an immediate red flag for me.  With Euphony, there is no option to set CPU frequency, isolate cores, or bridge LAN ports but it does give the user a polished and easy to use interface.  Where AudioLinux is a tweaker's dream, Euphony was designed for those looking for a more no fuss turnkey solution.  Having spoken by phone with Željko Vranić, one of Euphony's programmers, he said their focus was to lower OS latency as much as possible which really has been Piero's goal at AudioLinux also but it would appear that they have approached latency differently.  Željko told me Euphony makes no attempt to isolate cores or to adjust the CPU frequency since they found this made no difference.  This certainly has not been my experience with AudioLinux.  After comparing the two, at this time, I am getting better SQ with Euphony than AL, especially on the server, and I must say this comes as a surprise, especially since Euphony doesn't allow me to bridge the 2 LAN ports on my JCAT card.  As both products utilize ArchLinux as its platform, I'm confident that AL will continue to evolve and that parity will become possible but thus far, I have been unable to configure AL to match Euphony's performance.  Ultimately, competition is good for the consumer and as I now own both products, I am rooting for both to succeed.

 

I apologize for this War and Peace length post.  It's unlikely you'll see a post like this from me again as I have grown tired of doing comparisons.  Best wishes to all.

 

Wow.. I nominate this post for post of the year, no decade! 😎

 

Thank you so much Romaz for the very extensive write-up and being such a great inspiration!

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5 hours ago, romaz said:

X Factor - Furutech Nano Liquid

 Upon completion of my build, I immediately tried powering on this server but it wouldn't power on.  My first thoughts were that this contact enhancer had somehow caused a short or ruined the board but I decided to wait 24 hours to see what would happen.  To my relief, after 24 hours, the board powered on but the board was only seeing one 4GB RAM stick and not the other.  

 

Great post. Thanks!

 

Regarding contact enhancers, I had a similar experience using Silclear, which is paste-like and contains silver. When I used it carefully and also sparingly on my vacuum tube pins the paste got pushed up to the top of the pins and caused enough electrical leakage that once I removed the Silclear I got a dramatic improvement in SQ! I have since removed it where I could.

 

I do believe that it can improve SQ but would caution that using too much can cause inadvertent bridging of electrical connections and definitely fry some types of devices...

 

 



"Don't Believe Everything You Think"

System

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5 hours ago, romaz said:

It's been a long time and so forgive me if I have a lot to say.  

I apologize for this War and Peace length post.  It's unlikely you'll see a post like this from me again as I have grown tired of doing comparisons.  Best wishes to all.

 

Wow, what an amazing post, Roy! Thanks so much!

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Roy, very informative post.  Regarding your surprise at Euphony's SQ, is that also despite the fact that your Euphony use was with an SSD?.

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6 hours ago, romaz said:

It's been a long time and so forgive me if I have a lot to say.  As I indicated in one of my last posts back in 2018, I wouldn't post again unless I felt I had something meaningful to offer.  I have received a lot of inquiries about the status of my audio setup and I apologize as I have not responded to most of these inquiries due to time constraints.  To be honest, since I started this thread back in 2017, my system has been in continual flux but the time has come hopefully to settle down for awhile and so I felt it was finally time to share the status of my setup and to offer some personal observations based on my comparison testing.  This marks my first public post since CA became Audiophile Style.  I miss just being able to say "CA" and having the audiophile community know what I am referring to.

 

As always, what I have to share are personal observations and opinions based on my sensitivities and personal preferences.  I have no financial motivations.  I have 2 systems at home and what works well in one system doesn't always work well in the other.  In other words, YMMV.

 

As for my 2 systems, they are as follows:

 

In my home office, I have a pair of near field desktop monitors that were custom made for me by Louis Chochos of Omega Speaker Systems based in Connecticut.  They cost me <$2k and they remain one of the highest value purchases I have ever made.  They are comprised of Louis' high efficiency, crossover-less Alnico drivers and excel in delicacy, nuance, and tone.  I am continually amazed by how well these drivers express the subtlest textures.  I used to own a pair of custom made Voxativs that were even more resolving and oh so velvety smooth but also a tad bright and not ideally suited for long term near field listening and so those are now gone.  Paired with a fast JL Audio Fathom F110 V2 subwoofer and driven directly by a Chord Hugo TT2 / Hugo M-Scaler, I find this Omega setup to be very transparent, highly resolving, non-fatiguing, and transfixing.  I own or have owned many fine headphones over the years (SR-009, HD800/HD800S, HE-1000 V2, Abyss 1266, LCD-4, Focal Utopia, Dharma D1000, TH-900) and when my children were living at home before they moved off to college, I found myself forced to headphone listening at night but my headphones have been collecting dust for some time because I have found my Chord DAC directly driving these Omegas to be that much more engaging, even at low listening volumes. 

 

With my youngest son having moved out of the house and onto college late last year, my big listening room is where I do most of my listening these days.  This room has been home to a lot of different speakers over the years and for most of the previous year, I was using a pair of large Martin Logan Renaissance 15A hybrid electrostats.  Typical of line source, dipole speakers, these Martin Logans cast a giant ambient sound stage and are wonderful for recreating large venue performances at full scale.  Driven by a Pass Labs X350.8 amp and XP-22 preamp, this setup excelled in beauty but ultimately lacked in resolution and transparency even when fronted by my Chord DAVE DAC with M-Scaler.  These giant electrostat panels, while very fast and with exceptional clarity, created a softly focused image and so point sources like a solo cello or a solo vocalist sounded too diffuse, too tall, and too wide for my tastes, regardless of speaker position.  As I made tweaks in my upstream setup, I could hear changes, however, I could hear these changes much more succinctly with my inexpensive Omegas and so for someone who values transparency, this drove me nuts.  Imaging and focus improved considerably with a switch from Pass Labs amplification to a more resolving Luxman M-900U/C900U and ultimately to Soulution amplification.  Imaging and focus further improved dramatically when I moved from a Shunyata Triton V3 to a Sound Application TT-7 line conditioner by Jim Weil but despite these improvements, I eventually came to the realization that I was not meant for line source speakers like electrostats or planars like my brother's Maggies.  Don't get me wrong, these are wonderful types of speakers with tremendous appeal but my time with the Martin Logans have better educated me as to the type of listening I prefer and so I have moved on to point source speakers once again in my large listening room, specifically the Wilson Alexia 2s.

 

I offer the above details for the following reason.  It's important to understand the context by which my observations and opinions are based and the priorities that I value as your priorities may be different.  I'm guessing that we all claim live music as our reference and yet it's interesting to see how we each vary in our approach to achieving the recreation of a live performance.  Because today's technologies remain incapable of faithfully reproducing a live musical performance and because we each are constrained by a budget, it helps to know what type of listener you are to understand which compromises you should accept above others.  My goals, simply stated, are resolution and transparency in the absence of harshness.  I aspire to beauty, organic, natural, and musical just like everyone else but these qualities are more in the eye (or ear) of the beholder and are not easy to define.  I tend to run from things that are described as warm (meaning slow), thick, heavy, euphonic, or lush.  Not that I don't like warm or lush, I just don't want everything sounding warm and lush if warm and lush aren't in the recording.  Just not me.  I find that if you can successfully address harshness at every step in your chain, there's usually no need to embellish or to colorize.

 

Moving on, here's a story about listening that some will find interesting.  There are 2 types of listening that most of us do.  There is critical listening where we focus on what we are hearing hoping to dissect the qualities of a performance, recording, or some piece of equipment and then there is pleasurable listening where the goal is to relax and to escape.  Given the choice, I'm sure most of us would prefer the latter.  Almost a year ago to this day, I hosted Rob Watts (who needs no introduction), Jay Luong (lead reviewer for AudioBacon.net), and Jim Weil (owner of Sound Application and designer of SA's line conditioners) in my home for a series of listening tests.  What I respect about these 3 gentlemen is that they are each highly educated and accomplished electrical engineers but also passionate music lovers.  It has been my experience that most engineers aren't true music lovers, don't know how to critically listen, or worse, they're closed-minded with fixed ideas about how digital electronics are supposed to sound based on theory alone.  Not these gentlemen.  

 

Rob had come all the way from Wales and brought along prototypes of M-Scaler and Hugo TT2 for us to listen to and for the better part of 5 days, we conducted a series of critical listening tests.  We did a lot of listening, both sighted and blinded, to Rob's prototypes, to different DACs, amps, cables, line conditioners, and speakers.  While it was a lot of fun to hang out with these individuals, our listening sessions were often more tedious than enjoyable.  We listened to select portions of Mahler's 1st symphony so many times that I couldn't listen to this symphony again for months.  What I found fascinating but not surprising is that while we each heard differences, we heard them differently and had different preferences.  Jim Weil had a strong aversion to anything bright.  Rhodium and silver-plated copper are Jim's enemies and he could sniff them from a mile away.  Jay Luong was especially sensitive to tone and timbre and would gladly trade detail for warmth.  Rob was particular to depth.  An organ that was 30 feet away had to sound as if it was 30 feet away.  Everything else was secondary and so not surprisingly, his DACs excel in depth accuracy.  My sensitivities are more toward transient response and the air and space around voices and instruments.  I also crave variation over harmony.  Even 2 Stradivariuses should never sound exactly the same and a system that makes them sound exactly the same simply isn't transparent enough.  We are who we are and so gear will speak differently to each of us.

 

Single box server vs server + endpoint

 

There are compelling examples to support either strategy.  In the perfect world, I would love to have the convenience of a single box solution but I have yet to hear a single box solution that I prefer over a multiple box solution.  With multiple boxes, there is the option for finer level tuning which I will discuss further but ultimately, it comes down to how well each box can be powered.  If all I can come up with is a single good PSU, than a single box server is all that I will aspire to.

 

The Endpoint

 

Those who have followed this thread from the beginning know that its original goal was to figure out ways to improve endpoints like the sMS-200 or microRendu.  It's amazing how endpoints have evolved since January 1, 2017.  The concept behind the endpoint was to create a low noise rendering device to interface with the DAC that isolates against noise generated by a powerful computer server.  Low noise was the rationale for using low power processors like ARM-based CPUs and even Celerons.  It was also the premise behind the avoidance of other noisy components like SSDs and switching power supplies.  While some of these principles have passed the test of time, others have not, at least not to my ears.  Low power CPUs are not necessarily what sound best.  How else can I explain how an i7 NUC board with its noisy switching regulators can sound better than an ARM-based sMS-200ultra or ultraRendu?  How else can I explain how an i7 NUC can sound better as I ramp up CPU clock frequency?  It's completely counter-intuitive but it suggests that aside from noise, there is performance to consider and sometimes performance requires power and sometimes performance is more important than low noise.  To my ears, an i7 has the potential to sound more spacious, fuller, and more dynamic than a Celeron or ARM-based CPU and the number of physical cores, CPU frequency and size of the CPU cache seem to matter.  The downside of the i7 is that they are potentially more challenging to power well.

 

Thus far, I have tested 5 NUC boards comprised of either a Celeron, i5, or i7 CPU and ranging from 2-cores to 4-cores and from 2MB of standard CPU cache to 8MB of SmartCache.  The best sounding board I have heard thus far is the NUC7i7DNBE based on an 8th generation i7 that I first discussed a few months ago.  

 

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I am open to the idea that a more powerful, non-NUC device could sound even better as an endpoint but once again, powering it would be the challenge.  Here is the Asrock IMB-1215 which will be released to the U.S. in a few months.  

 

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It is a mini-ITX board that can accommodate an 8th or 9th generation i7 and with an open PCIe slot that can be powered by a single 19V rail and so I find this board to have intriguing possibilities.


SOtM has reportedly designed an i7-based motherboard from the ground up with high level clocks that can be powered by a single 19V PSU.  I very much look forward to trying out this board.  

 

The NUC7i7DNBE when purchased as a board are more difficult to come by and also more expensive at a price of around $650 USD.  Ironically, the NUC7i7DNKE NUC kit, which houses a NUC7i7DNBE board within a standard Intel chassis are much more readily available and cost $100 less.  I just purchased one a few weeks ago and it took all of 5 minutes to explant the NUC7i7DNBE board from the chassis.

 

The NUC7i7DNBE has the option of being powered by a 12-24V PSU and higher voltage DEFINITELY sounds better to me.  Bigger and more dynamic.  It also has the option of being powered via either a 2.5mm x 5.5mm barrel connector or 2x2 mini Molex connector.  With 2 NUC7i7DNBE boards on hand, I was able to recently do a direct A/B and powering via the 2x2 Molex connector sounds very slightly better.  

 

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As for power supplies, I could not successfully power a NUC7i7DNBE board with a single LPS-1.2 at 12V even though my Kill-a-Watt meter suggests this board never consumes more than 8 watts during bootup.  I could get it to post to the BIOS screen but even with Turbo and Hyperthreading turned off and with only 4GB of RAM installed, I could not successfully boot into AudioLinux from a USB stick.  I purchased a special serial Y-cable from Ghent Audio and this allowed me to combine two LPS-1.2s and this worked.  The cable that I had Ghent make for me is comprised of high quality Neotech 18g 7N OCC copper and so I spared no expense to get it as I was very excited by the prospect of being able to power the NUC with 24V using two LPS-1.2s set at 12V each.  

 

Unfortunately, for reasons that remain a mystery, I could not get this to work.  Each time, one of the LPS-1.2s would start to blink red during the boot process and turn very hot.  I own three LPS-1.2s and regardless of which one I swapped in, one of the LPS-1.2s would start to blink red and it was not always the same LPS-1.2 that would give out.  When I kept one LPS-1.2 at 12V and switched the other to 9V (12V + 9V = 21V), this somehow worked and the NUC booted just fine.  19V (12V + 7V) also worked.  The problem with using two LPS-1.2s in serial is that they don't sound good at all and this was very disappointing.  In fact, I found better SQ powering the NUC with the 19V rail from my HDPlex which came as a surprise.  It appears that using 2 or more LPS-1.2s in serial is not a good thing to do.  The NUCi7DNBE also likes headroom and the LPS-1.2's 1.1A of headroom is a limitation.  To hightlight the importance of headroom further, a 12V SR4 sounds very good powering this NUC but a 12V SR7 with its greater headroom sounds even better.  

 

Beyond headroom, the avoidance of any voltage drop is also very important and a 12V DR (double regulated) SR7 sounds better yet although I am getting my very best SQ with this NUC powered by a 19V SR SR7 rail.  With this NUC powered by the 19V rail from an HDPlex 400W ATX LPSU, while the SQ is not in the same league as an SR7 or even the SR4, it is much less harsh than the stock 19V switcher that Intel provides and so the HDPlex is more than just a passable option.  The JS-2 or a bespoke PSU from either Sean Jacobs or Adrian Wun at TLS could be even better options but at a cost.  As I stated above, the downside of the i7 is that they are potentially more challenging to power well but I do feel the rewards are there.

 

As for clocking, not surprisingly, this makes a significant and worthwhile difference.  I had the TLS DS-1 on hand for a few months and it's single OCXO reportely replaced 3 clocks on this board (system, Ethernet, USB).  

 

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While much has been made about the mediocre performance characteristics of the Connor-Winfield OCXO that Adrian at TLS likes to use for all of his products, the removal of 3 noisily powered clocks from this board and replacing it with a cleanly powered clock even if that clock is of suspect performance has paid significant dividends.  I had a stock NUC7JYH board with its Celeron J4005 CPU on hand and it is the very same board and CPU that Adrian used for the DS-1.  Direct A/B revealed a significant uptick in detail clarity and spaciousness with the DS-1.  Compared against my stock NUC7i7DNBE, this superior detail clarity was still very much evident although I found the i7 NUC to sound more spacious still.  Regardless, I heard enough to know that it would be worthwhile to send my i7 board to SOtM for clock replacement and indeed, it has been worthwhile.  To have replaced the 4 replaceable clocks on this board has resulted in a notable decrease in harshness resulting in cleaner transients, better definition, more accurate timbre, and a greater sense of space.

 

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However, the benefits of clocking have to be placed in proper perspective.  To my ears, the power supply still makes the bigger difference.  I have the benefit of having 2 NUC7i7DNBE boards on hand (one is stock and the other has been reclocked) and this has allowed me to make careful A/B comparisons.  With the stock i7 NUC powered by a 19V rail from my SR7, I am getting better SQ overall than the SOtM-modified NUC powered by the 19V rail from the 400W HDPlex.  If forced to choose, the choice would be easy.

 

The Server

 

With my inaugural post on this thread, I had described my observations about how LAN bridging resulted in increased transparency of the endpoint to the upstream server.  While the mechanism for why this improves transparency remains unsettled, with bridging, it was clear to me that the quality of the server mattered.  With the release of the SOtM sNH-10G switch last year, I reported that I was no longer able to differentiate between the Zenith SE and my noisy 12-core Xeon-based Mac Pro when either one was used as a Roon server.  But that was before AudioLinux came into the picture which allowed me to play with CPU frequency settings and this has made all the difference.  The Zenith SE houses a powerful and low noise PSU but it is mated to a very weak Celeron while my Mac Pro utilizes a noisy switching PSU mated to a much more capable 12-core Xeon with a giant CPU cache.  Without any OS manipulation of the CPU, cursory A/B comparisons between the two yielded no significant difference to my ears suggesting that the sNH-10G had effectively blocked the higher noise that was being generated by my Mac Pro.

 

But what would happen if I pushed my Mac Pro's CPU clock from it's base idle frequency to max turbo levels?  Of course, this is the beauty of AudioLinux and it has proven to be a very useful learning tool.  With higher CPU frequency, dynamics goes up but at the expense of subtlety and nuance and with progressively increasing harshness and the sNH-10G is incapable of completely isolating against these changes.  I have read commentary that the upcoming opticalRendu will supposedly be completely immune to the virtues of the upstream server.  I suspect this is probably the goal of the upcoming EtherREGEN also.  Well, I believe this is both naive and wishful thinking and so people will need to adjust their expectations appropriately or else they will be disappointed.  

 

I say this because I currently have 2 SOtM sNH-10G switches in my possession and I can tell you that while 1 switch makes a very big difference, 2 switches make an even bigger difference.

 

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What is nice about these switches is that they have both standard RJ-45 Ethernet ports as well as optical Ethernet ports and so with these switches connected by a single-mode fiber optic cable, here is what I found.

 

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With the optical cable compared against a 50+ foot Blue Jeans Cables CAT6A Ethernet cable, the noise floor with the optical cable was noticeably lower and there is a clear preference for the optical connection.  With the optical cable compared against a 22-foot Belden CAT6A cable with JSSG360 shielding that was made for me by Ghent, the gap was smaller but there was still a slight preference for the optical cable.  With the optical cable compared against a heavily shielded 1.5m SOtM dCBL-CAT7 cable, the noise floor was equivalent (at least to my ears) but tonality with the SOtM cable sounded more natural.  The optical cable sounded a touch thin and bright in comparison and so in this instance, the copper Ethernet cable sounded better.  Regardless, in each and every comparison, optical or otherwise, if I varied CPU frequency, I could hear differences in the server.  The server still ABSOLUTELY matters and this is because it's not just about noise, there is also the matter of performance and it would appear that RoonServer likes horsepower.  At this time, the delta I am hearing from my best server setup to my worst server setup is about the same as the delta I am hearing from by best endpoint setup to my worst.  In other words, my current stand is that the server matters as much as the endpoint.

 

CPU

 

My testing has shown me that modern CPUs are preferable to older generation CPUs  A few generations ago, an i7-4790 yielded a TDP of 84w with 4-cores/8-threads, 8MB of SmartCache and CPU turbo speeds reaching 4GHz.  Today, an i7-8700T yields a TDP of only 35w but offers 6-cores/12-threads, 12MB of SmartCache and CPU turbo speeds reaching the same 4.0GHz.  Basically, more performance with less noise and A/B comparisons between these 2 CPUs reveal exactly that.  An 8700K houses potentially even greater performance with a max turbo rating of 4.7GHz using better binned parts according to Intel and so I decided to compare this against the 8700T.  

 

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Ultimately, it didn't seem to matter since I heard no benefit clocking either of these CPU beyond 3.8GHz when powered by the HDPlex 400W ATX LPSU due to harshness but who knows what would happen if I had a better ATX PSU on hand?  I have explored such a PSU with both Adrian Wun of TLS and Sean Jacobs but the cost of a "no compromise" ATX PSU from these gentlemen will run somewhere in the $4-5k range. Regardless, the CPU matters and if I were to build another server, I would probably go for a standard i7-8700 since they're more readily available and less expensive then either the 8700T or 8700K.

 

Motherboards

 

My testing has shown me that the motherboard matters also.  Borrowing a page from Pink Faun's book that gaming boards can sound better, I decided to compare a standard Asrock Z370M-ITX/ac motherboard against an Asrock Z390 Phantom Gaming-ITX/ac motherboard.  

 

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First of all, I only looked at Intel boards since it wasn't clear to me that an AMD board was compatible with Optane memory.  Second, I specifically targeted the Z370/390 chipset because these chipsets were capable of running the latest generation i7s (both 8th and 9th gen).  The Z390 board happened to be designed for gaming meaning they were engineered to be overclocked.  As such, this gaming board has an 8-layer PCB with a whopping 8oz of copper to maximize conductivity and to enhance the ground plane.  This board also has beefier heat sinks to improve heat dissipation and a more robust VRM (voltate regulator module) to make sure the CPU is never starved of current.  While the differences weren't large, the gaming board had more substance to the sound stage with greater authority to its presentation but not to be completely outdone, the Z370 board had a touch better finesse and subtlety.  The point is that even these more minor differences were easily audible in the server.

 

SSD vs Optane

 

Just for kicks, I decided to compare a 58GB Optane card against a Samsung 500GB 960 EVO NVMe SSD in the M.2 slot of the Asrock board.  This was a very brief comparison because it didn't take long to realize how much more harsh the SSD sounded even with all of my isolation schemes in place.  It's amazing how many commercial music server manufacturers continue to use SSD drives in their servers as if powering an SSD cleanly somehow addresses this harshness when it does not, at least not to my ears.  I suppose you get used to the harshness over time but an SSD is about the worst thing I can imagine putting into a music server with the super fast NVMe drives sounding the harshest of all.  As some may recall, in previous testing, I found the older, slower SATA II SSDs (especially the SLC variety) to sound less harsh then the newer, faster SATA III SSDs although the faster SATA III SSDs made music sound more alive and more immediate and so there was a trade off.  It would appear that the Optane cards have the best of both worlds and so hats off to Larry for introducing us to the Optanes.

 

I have read comments about how running AL in memory doesn't result in much improvement in SQ except for a slight improvement in smoothness.  The point here isn't just running AL in memory for the sake of latency but also to be able to completely avoid using an SSD in the server.  The Optane seems to be a nice compromise if capacity, low latency, and low noise are desired since Optane behaves more like RAM than an SSD.  For those with a large Roon database who are looking for a brisk user experience with Roon, an Optane drive may be preferable to a USB stick for the Roon database.  For sure, it would be preferable to an SSD.  From a SQ standpoint, is an Optane drive preferable to having more RAM (16, 32, or even 64GB)?  I'm not sure although according to Intel, a 58GB Optane drive only consumes 3.5w and so it would appear to draw much less current than RAM as a 3.3V device.

 

RAM

 

I haven't done much testing with memory to see what is ideal.  Apparently, Sound Galleries has found that RAM timing matters with respect to SQ but they are keeping mum about what they found to be the ideal RAM timing for their servers.  It made sense to me to target low latency memory and I have had good success as far as compatibility with Kingston's HyperX DDR4 for either Asrock board and for the i7 NUC but I haven't yet played with RAM timing.  As I previously posted, I have not been able to distinguish any difference in sound between 4GB vs 8GB or single channel vs dual channel memory and I believe these findings are supported by the findings of others.  I have been asked about using as much as 64GB of memory in the server.  I have to wonder what the benefits of using large amounts of memory are except for the purposes of a RAM drive to store music since AudioLinux doesn't even occupy 4GB when ramrooted.  According to Crucial, both DDR3 and DDR4 memory consume about 3 watts per 8GB.  That means 16GB consumes 6 watts and 64GB consumes 24 watts.  As 1.2V devices, that represents quite a bit of current draw.  In fact, 24 watts is more than the whole i7 NUC board consumes and while RAM isn't as noisy as an SSD, I have to guess that this amount of consumption is going to result in increased noise in the ground plane.  While storing or caching music files in RAM seems to lead to a slight increase in SQ with AL (a touch more smoothness), I would have to guess that any gains made would likely be offset by the noise created by that much RAM.  I think even 16GB offers no SQ advantage for 2-channel audio, even with OS's that pre-fetch all streaming music into memory (i.e. Euphony).

 

Ethernet - JCAT Femto Network Card

 

I've already provided my experience with optical Ethernet in the SOtM sNH-10G switch and I suspect it would apply to a LAN card one might use in a server also.  With long runs of cable, optical seems to provide an advantage but with short runs, optical has potentially no advantage or actually sounds worse.  This suggests to me that much of the noise that optical is mitigating is coming from the Ethernet cable and not the server and that with short runs of Ethernet cabling or with well-shielded cabling, the higher amounts of jitter that optical creates now becomes its Achilles' heel.  Regardless, even in the best case scenario where optical imparts a benefit (i.e. when compared against a 50+ foot run of Blue Jeans Cables CAT6A), the improvement pales in comparison to what I am hearing with the JCAT Femto Network card.  The JCAT card is a game changer.

 

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I looked at other cards, specifically TLS's LAN card with OCXO but I decided to go with the JCAT card because it had 2 Ethernet ports that I could bridge and because it was the only card I could find that I could independently power with an outboard PSU.  Adrian at TLS told me his network card had redundant linear regulation on board and so bus power should sound as good as an outboard PSU but I refused to believe it.  It just so happens that the JCAT card has the option of either being bus powered or being powered by a 5V outboard PSU and so it was easy to do this comparison.  No surprise, this card when powered by a 5V SR4 sounds incredibly better than bus power.  What did come as a surprise is that the LPS-1.2 is not a good choice for the JCAT card.  To power both Ethernet ports, you need to feed this card at least 1.5A according to Marcin although the LPS-1.2's 1.1A is enough to power one of the Ethernet ports.  The problem here is you not only lose the option of bridging but SQ was just not great because the LPS-1.2 sounds like it's working too hard just to power the one port.  The noise floor is low and articulations are clean and clear but they sound weak and thin.  Even the 5V port from the HDPlex sounds better overall.

 

Not to knock the LPS-1.2 since I regard this PSU very highly and in fact, I own 3 of them but I find that components that draw anywhere close to it's max rating of 1.1A aren't going to sound that great powered by the LPS-1.2.  Also, there are some components that just benefit tremendously from headroom.  A good example is the sNH-10G switch.  The LPS-1.2 powers it fine but it doesn't power it great.  This switch really scales with a 12V DR SR7.  At a minimum, I would suggest an SR4, otherwise, you may feel underwhelmed with this switch.  I imagine the upcoming EtherREGEN will be a better match for the LPS-1.2.

 

Chassis - HDPlex H3 V2 

 

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This proved to be an excellent chassis in many ways for my intended build.  First, it is a fanless chassis capable of dissipating 80w of heat according to HDPlex.  Testing with an i7-8700K running for extended periods at a fixed 4GHz showed that this case could handle that level of CPU just fine.  At no time did CPU temps climb beyond 65 degrees C, however, at that speed and at those temps, harshness was quite evident.  Second, and more importantly, the design of this chassis allowed for the utilization and easy comparison of different outboard ATX power supplies.  The key word here is outboard.  Despite the greater impedance that comes with having to use long umbilical cabling with an outboard PSU, I have found digital components to be very sensitive to vibration and to house a large vibrating transformer in the same chassis as the server is fundamentally against my design philosophy and among the chief reasons I struggle with single-box servers, at least on theoretical grounds.  My former Innuos Zenith SE did a good job isolating the impact of it's large 300VA transformer on the rest of the server but as we know, when it came time to build their no-compromise Statement server, Innuos felt they had to separate the PSU from the main chassis.  If there is a downside to the H3, it's build quality is not to quite to the same level as the fanless cases by Streacom but, nonetheless, it is a solid chassis and nowhere as resonant as many of the Akasas.  Like with all my digital gear, I find that this chassis benefits from good vibration dampening footers as they result in cleaner transients with tighter image focus.

 

One mistake that I did not make with this server that I made with my previous server is the use of EMI paper.  With my previous server build, for those that recall, I lined the whole chassis with EMI paper with the idea that if a little is better, a lot is better still.  Well, I found that too much EMI paper kills the sound and has the potential to sound lifeless and overly damped.  It turns out playing with the harmonic frequencies even at frequencies beyond the audible frequencies (>20kHz) has a very audible effect and so with this build, I have purposely shied away from using EMI paper.  If another used Tranquility Base shows up on Audiogon, that is what I will preferentially target.

 

PSU - HDPlex 400W ATX LPSU

 

I was so impressed by my i7 NUC endpoint with its clocks replaced and powered by a 19V SR7 that I wondered what it would sound like to have the same i7 NUC with the same clocks replaced and powered by a 19V SR7 as the RoonServer.  Well, I tried this and it resulted in an exceptionally clean sound with wonderfully crisp and clear articulations and incredible detail resolution but somehow, compared against the either the 8700T or 8700K, the i7 NUC as a RoonServer lacked soul.  The more powerful machine sounded more dimensional, airier, fuller, more authoritative, and more real.  I went back and forth because each had its appeal but ultimately, the more powerful machine won out as my preferred Roon server.  

 

This led me to wonder how much of what I was hearing was the more powerful CPU vs the PSU.  Was the HDPlex 400W ATX PSU really that good?  I decided to power the i7 NUC with the 19V/10A lead from the HDPlex and even using a custom JSSG360-shielded OFC DC lead made for me by Ghent, compared against the 19V SR7, the HDPlex was a fairly significant step backward.  Noise floor was higher, bass sounded bloated and ill-defined, mids sounded a bit muffled, and treble sounded rolled off.  Not to say the HDPlex sounded horrible (as I previously mentioned, the HDPlex is actually more than just passably good), it's just the 19V SR7 is that much better. 

 

This outcome is a good example of performance being more important than low noise.  When I first described my experience with an unmodified NUC (with AudioLinux) sounding better than a microRendu or sMS-200, people wondered how devices that were built from the ground up for audio playback with high level clocks and low noise regulators could be bested by a cheap NUC.  My only explanation is that low power CPUs like ARM-based processors leave a lot of performance on the table and with Roon Core or RoonServer, I believe this all the more true.  It turns out horsepower isn't beneficial only for upsampling with HQP.  I'm sure this comment will stir a lot of debate and even heated comments but unless someone can propose a better answer, this is what I'm going with.  

 

Some will ask why I didn't go with the 200W HDPlex LPSU when this server consumes no more than about 50 watts max and more typically about 30 watts.  First, I wanted as much headroom as possible.  After speaking with Sean Jacobs, he was very much in favor of over-provisioning any ATX PSU he would design for me to avoid core saturation.  In fact, his design incorporated a 300VA transformer even though I told him I was expecting my server to only consume about 30-35 watts.  Second, I wanted to avoid a DC-ATX converter.  Having purchased and tried the HDPlex 400W DC-ATX converter already back in 2017, I was less than impressed with its performance even when powered by the 19V rail from my SR7.  Sean was also willing to share a few things about what he had learned regarding ATX PSUs (as we know, Sean designed the PSU for both the Zenith SE and the Statement).  According to Sean, the 5V rail is extremely important and requires high current for optimum performance (ideally 4-5A) even if you're not planning on powering any 5V devices such as an SSD.  Apparently, many parts of the motherboard utitilize this rail and unfortunately, the 5V rail on the 200W HDPlex outputs only 2A.  Even if I wished to bypass a DC-ATX converter and create special cables to directly power a motherboard, 2A of output, at least according to Sean, would be less than ideal.

 

As I started doing my listening tests with the HDPlex 400W ATX LPSU, I compared it against a Corsair RM650X ATX PSU.

 

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I specifically chose this 650w Corsair because it had comparatively low ripple noise measurements and very good voltage stability and indeed, before the arrival of the HDPlex, I was quite impressed by its performance.  I wasn't sensing any of the fatiguing harshness I had heard with my Mac Pro or HP workstation.  Against the HDPlex, the Corsair was no match, however.  Noise floor was even lower but the sound signature was also fuller, more dynamic, and harmonically richer.  

 

As I was building servers for others, I had the good fortune of having 2 HDPlex 400W ATX LPSUs on hand and so I got a chance to use both at the same time.  

 

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I used one HDPlex to power the motherboard via the 24-pin ATX connector and the other HDPlex to power the CPU via the 8-pin EPS connector using custom shielded cables made for me by Ghent.  This resulted in further significant improvement -- even better low end dynamics and a more substantial sound stage.  Is it worth another $800 to buy a 2nd HDPlex?  I have to say that it's a very tempting proposition and something worth considering because the difference is there.  Because I had an older 200W HDPlex on hand, I decided a few days ago to try powering the CPU from the 12V lead of this HDPlex using the same custom XLR cable that Ghent made for me and unfortunately, with the 8700K, the 400W HDPlex sounds more dynamic by itself.  I'm sure that a bespoke ATX PSU built by Sean or Adrian would be even better but for $800, I am very impressed with the HDPlex 400W ATX LPSU.  

 

X Factor - Furutech Nano Liquid

 

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This needs to be filed under the "needs to be heard to be believed" catergory.  I received a tip awhile back from a trusted friend to give the Furutech Nano Liquid contact enhancer a try.  Those that know me know that I use a full loom of High Fidelity Cables everywhere except for USB and that's only because High Fidelity Cables don't make USB cables.  Anyway, as good as HFC cables are, I was very impressed by how this Furutech contact enhancer, which is basically a proprietary formulation of silver and gold particles suspended in squalene oil, resulted in an even smoother, richer, and more liquid presentation.  Yes, I know, it wreaks of voodoo but I loved what I was hearing.

 

For my initial server build using the 8700T CPU, I decided to cautiously apply this contact enhancer to the CPU, RAM, Optane card, JCAT card, and the ATX and EPS connectors.  Upon completion of my build, I immediately tried powering on this server but it wouldn't power on.  My first thoughts were that this contact enhancer had somehow caused a short or ruined the board but I decided to wait 24 hours to see what would happen.  To my relief, after 24 hours, the board powered on but the board was only seeing one 4GB RAM stick and not the other.  I switched around the sticks and it became clear that the RAM itself was not the problem but slot 2 on the motherboard was somehow not functioning or at least not detecting RAM that was inserted into this slot.  Was this a defect in the board or a result of the Furutech Nano Liquid?  I'm not sure but I wasn't bummed long because the SQ I got from this server was beyond what I was expecting.  Was it the CPU, the JCAT card, the HDPlex ATX PSU, or the Furutech liquid that was responsible for the magnificent sound?  It was impossible to know for sure.

 

I was asked to build a second server for a friend similar to this first server.  With this second server, I strongly suggested the Asrock gaming ITX motherboard and the i7-8700K.  As I mentioned above, I believed this particular motherboard should, in theory, sound better than the first board because it had more layers in the PCB, more copper in the ground plane, better heat sinking, and a more robust VRM.  Because the 8700K was structurally identical to the 8700T, they should operate similarly but because the 8700K used better binned parts, I reasoned that the 8700K could potentially perform better or at least more durably since I would intentionally be running this CPU well below it's rated peak capability of 4.7GHz.  Not wanting to risk the same headache, I elected not to apply the Furutech Nano Liquid to this build, at least not initially.  The machine powered up fine and with what I thought were appropriate expectations, I was quite let down by what I heard.  It sounded very dynamic but there was a dryness and a harshness to the sound that I wasn't hearing with my other server.  I quickly moved back to my other server and this was immediately confirmed.  My other server sounded smoother, more liquid, and harmonically more pleasing.  

 

Despite 100 hours of burn in, the new server failed to come close to what I was getting with my other server and so I had to let my friend know these findings.  I told him I couldn't say for sure but I didn't think it was the 8700K that was the culprit since I was getting the same temperature readings based on the frequency I was running compared against the 8700T.  I postulated that it had to be either the motherboard that was the culprit or else the Furutech Nano Liquid was the missing X-factor.  I offered him the option of applying the Furutech Nano Liquid but he would have to accept the risk that this liquid could damage his motherboard.  He agreed and so I tore down this machine and started over, this time more copiously applying the Nano Liquid to the CPU, Optane card, RAM, JCAT card, and ATX/EPS connectors.  Since I was given the green light, I figured if we were going to go down and be forced to buy a new motherboard, we might as well go for a home run.  Well, after application of this Furutech liquid, this server did improve...dramatically...and it was noticeable immediately.  If I have to guess, it is with the CPU where this liquid makes the most difference.

 

Operating System - AudioLinux vs Euphony

 

It would be a gross understatement to say that I was merely pleasantly surprised when I first heard a NUC running AudioLinux in RAM and I have Adrian of TLS to thank for this.  What is just as impressive is how open-minded and responsive Piero has been to suggestions and so it has been amazing to see how AudioLinux has evolved in such a short amount of time.  Rajiv and I had asked Piero to allow us the ability to specify CPU frequency and the ability to tune the CPU frequency has been extremely educational.  It also allows for the utilization of just about any CPU since the user is no longer tied to just the base frequency or the peak turbo frequency of a CPU.  Regardless of whether you're using an 8700T, 8700, or 8700K, you can dial in almost any frequency from 400MHz all the way to >4GHz and so with just about any CPU, it becomes a matter of the number of physical cores and the size of the cache.

 

As you go up in frequency, dynamics improves but it is at the expense of subtlety and nuance and at some point, harshness will set in.  I have found that harshness sets in sooner with lower quality PSUs.  With the HDPlex, I can push to 3.8GHz with the 8700T/K before the harshness gets unacceptable.  With the SR7 powering the i7 NUC, I can push as far as the i7-8650U will go (maxes out at 3.8GHz even though Intel claims it can go to 4GHz) and unacceptable harshness never really becomes an issue but this depends on the server CPU frequency.  What is fascinating is that with my large orchestral tracks, I had a preference for running the server at 800MHz which gave me my very best detail while running the NUC endpoint at 3.8GHz which gave the sound more body.  With heavily amplified rock, I found the server sounded best at 3.2GHz and with the NUC endpoint at about 2.2GHz.  It seemed that with the server running at a lower CPU clock speed, the NUC endpoint was receiving a cleaner (less harsh) signal that it could then amplify more agressively without penalty.  With the server running at a higher CPU clock speed, there was more body to the sound but as I advanced the NUC's clock speed, harshness became evident much sooner.  Regardless, to have this level of control has been amazing and I can tell you that these preferred settings apply only to my large listening room with my Wilsons and not to my smaller listening room with the Omegas.  I'm also convinced these settings would be different had I still had my Martin Logans.  

 

This is also the beauty of the core isolation feature and being able to switch between RoonBridge and Squeezelite on the endpoint.  Core isolation in my system results in a tidier and more precise sound signature resulting in tighter focus but at the expense of bloom.  With my Martin Logans, I would have had core isolation tuned on in both the server and the endpoint but with my Wilsons, it sounds too mechanical and so I leave it on in the endpoint but off in the server.  Squeezelite is similar to my ears.  It is a cleaner and more precise presentation whereas RoonBridge can sound more uncontrolled with undersirable overhang but for certain types of music, Squeezelite can sound less natural and overly sterile.  Regardless, I like the option of being able to easily switch between the two.

 

A couple of weeks back, I decided to give Euphony a try at the recommendation of a friend who was impressed with the upgrade from version 2.0 to 3.0.  Euphony lacks the fine manual controls that AudioLinux provides and so this was an immediate red flag for me.  With Euphony, there is no option to set CPU frequency, isolate cores, or bridge LAN ports but it does give the user a polished and easy to use interface.  Where AudioLinux is a tweaker's dream, Euphony was designed for those looking for a more no fuss turnkey solution.  Having spoken by phone with Željko Vranić, one of Euphony's programmers, he said their focus was to lower OS latency as much as possible which really has been Piero's goal at AudioLinux also but it would appear that they have approached latency differently.  Željko told me Euphony makes no attempt to isolate cores or to adjust the CPU frequency since they found this made no difference.  This certainly has not been my experience with AudioLinux.  After comparing the two, at this time, I am getting better SQ with Euphony than AL, especially on the server, and I must say this comes as a surprise, especially since Euphony doesn't allow me to bridge the 2 LAN ports on my JCAT card.  As both products utilize ArchLinux as its platform, I'm confident that AL will continue to evolve and that parity will become possible but thus far, I have been unable to configure AL to match Euphony's performance.  Ultimately, competition is good for the consumer and as I now own both products, I am rooting for both to succeed.

 

I apologize for this War and Peace length post.  It's unlikely you'll see a post like this from me again as I have grown tired of doing comparisons.  Best wishes to all.

Excellent comprehensive review! I agree this should be awarded, e.g. "review of the year"?   From what you said, I am not sure if you used Optane drive for your testing, correct? When you compared with Euphony, did you use AL in Optane or load into RAM ? I presume you did Euphony via USB stick, or was it internal SSD? I don't think it can run in Optane  M2 ? I am not really familiar with how optane

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