Mac Mini version of a CAPS music server - Step by Step

Thought I would share my findings for those with a Mac inclination and looking for good computer audio playback, and provide a bit of a step by step to make the Mac Mini a viable option for audio pleasure.

These are just my findings and the path I took. Of course there are many ways, and everyone’s situation and experiences are different. It is a bit of a long post, and some steps might seem excessive, but I hope at least some of it will help someone looking to use the Mac Mini in a similar fashion as the CAPS PCs. It helped me tremendously as I nearly threw in the towel on the Mac route.

It has been a long, frustrating job since I have been hell bent on building a solution around Amarra, and thus it had to be the latest Mac OS. I looked into Hackintosh route but that was far too complex for me.

The Mac Mini seemed to be a good place to start but it is inherently very noisy, and will envelop you, if sensitive to it, in listening fatigue, noise, etc. By noise, I do not mean the noise coming from the physical unit, although I would recommend sticking it in a closet far away from your sensitive DAC, pre-amps and analog cables, but digital hash, EMI/RFI related shite which to some will be heard as an increased noise floor, loss in spatial info, or increased listening fatigue. For me it actually hurts my ears and is a relief when turned off. It really is soooo much easier to get good sound out of a CD player. 

Step by Step

Thus in order to get convenience of iPad remote control, but non-fatiguing sound I had to take the following actions:

1. Buy the latest Mac Mini with Solid State Harddrive (SSD) for the OS and at least 8GB memory. (Some folks mention that using 1 stick as opposed to 2 will again lower the current taxation on the motherboard, but I went with 2 sticks). Don’t bother with fusion drives or an additional internal drive.

2. Buy Amarra software. I also bought Audivarna for comparison, which is much easier to use, does DSD (using DoP0) and is far less troublesome, but misses some spatial details that Amarra does have when listening.

3. Buy a Western Digital Thunderbolt Duo drive or similar. No USB drive. Firewire is fine too although Tbolt is faster, which I found out the hard way, is a necessity for Amarra. NAS Synology was a no-go with Amarra…too big a latency I guess. Plus that adds another avenue for electrical (e.g. common mode noise) crap to enter through the LAN connection.

4. Buy an iFixit Mac Mini Dual Hard Drive Kit (even though I did not use the dual hard drive connection…), since it has all the tools necessary to take the Mac apart with ease, and without breaking anything.

• Amazon.com : iFixit Mac Mini Dual Hard Drive Kit : Computers & Accessories

5. Get the iFixit guide for free and follow it for a complete tear down

• Mac Mini Late 2012 Teardown - iFixit

6. Buy a linear power supply to replace the Mac’s switching power supply (some estimated the ripple as 500mV) for 12V and 6 Amps. I bought a Keces DC-116 from Taiwan (check for the other threads for details)

7. Buy a 12V DC cable connection for the Mac 2012 to your power supply which is available through places like Item Audio or Paul Hynes in the UK, Mojo-Audio or Mod Audio in the US. Since I could not find shielded, I just use some foil to shield it.

• Mac Mini External Power Supply Modification Services

8. Buy or make a shielded DC cable, with the drainwire/shield connected on one end that will be connected to a ground/earth connection. This will go between the computer 12V cable to your linear power supply. You will need to get a few plugs as well (Keces uses 2.1mm by 5.5 mm)

Since you want to put at least a meter of distance from the linear power supplies and your Mac due to the big magnetic field on those LPSUs, size the cable accordingly. Making it yourself will cost about $5. To buy one that is all put together check these guys out:

• Revelation Audio Labs: power cables

9. Buy a SATA internal extension cable so that you can physically move the SSD away from the motherboard and allows for space to add an SOTM SATA filter

• NSIcable 22-pin (7+15) SATA Male to Female DATA and Power Combo Extension Cable - Slimline SATA Extension Cable M/F - 1Ft (33cm)

• Amazon.com: NSIcable 22-pin (7+15) SATA Male to Female DATA and Power Combo Extension Cable - Slimline SATA Extension Cable M/F - 1Ft (33cm): Computers & Accessories

10. Buy an SOTM SATA filter. This will tie to the SATA connector in the MacMini’ MOBO SATA connection, after which the 22 pin SATA extension cable is plugged into the SOTM filter, and finally the SSD. Do not put the SOTM filter directly on the SSD, as it will for some reason not recognize the HD anymore. In the US these guys are very quick:

• Sonore / SOtM

11. Shield the SATA cables, power and data separately. If you are ready to spend a lot more then there are a couple of places that make and sell shielded SATA cables – I have NOT tried these, as I thought using some simple shielding. This might be a bit controversial to some, but if it works for you, so what. I am all for less electrical and magnetic interference.

• JCAT | JPLAY - hi-end audio player for Windows

• paul professional audio studio

12. Buy some more shielded 12V cable (2/22 – 2 wires at 22 AWG gauge should be plenty) for the fan. You can buy a big cooling duct setup for passive cooling although I have NOT tried this. Instead I opted to keep the Mac Mini stock fan since it is quiet and metal but have it powered through a linear power supply instead of the motherboard.

Since the fan’s speed is normally controlled actively by the MOBO it changes the amount of draw constantly, which can introduce more noise. There is a good reason that the CAPS builds are mostly fan-less, and not only because of the whirring noise coming from the fan. With a linear bench PSU you can set the voltage to a lower setting determined by a bit of trial and error to get an ok temperature. I run it at just under 5V and get around 40 degrees Celsius during listening.

By the way, the two outer wires of the 4 are the power wires for the fan. You can, if you have the soldering skills and patience, buy the same clips used by Mac through a brilliant electrical parts store called Mouser Electronics:

• 78171-0004 Molex | Mouser

Molex Headers & Wire Housings – part numbers: 538-78172-0410 , 538-78172-0004, 78172-0004 , 538-78171-0004

13. Buy a simple linear power supply to power the Mac Min fan, for example:

• HY1503C Variable Linear DC Power Supply, Analog Display

14. Get a free temperature gauge software, which I would recommend not running in the background for serious listening, just to check if your solution will melt your CPU or not, is the following:

• smcFanControl (can download it from cnet)

15. Remove the following bits from the Mac (By the way, it is non-destructive and can always be put back in if you are careful with unplugging the wires)

• Switching power supply

• Wireless antennas. There are two of them (silver metal around 5x1cm) each with their own power lead.

• Airport/Bluetooth antenna

• Logic board assembly for the speaker

• Broadcom wireless circuit board (tiny about 1.5x5cm)

• IR remote antenna (hidden away a bit) Use the following iFixit guide to find it

Replacing Mac Mini Late 2012 IR Sensor - iFixit

• Cowling (plastic bit) – see the iFixit guide

• AC socket

16. Buy an Ethernet filter – Acoustic Revive RL-1 (Another reason to not have a NAS as this is not gigabit ready). Contact the following quality shop:

• Yohei Kojima at [email protected]

17. Replace CAT5 unshielded LAN cables with shielded Ethernet cables 6 or 7, as long as it is shielded. Big difference. You can ground it on one side to have the shield drain to the path of least resistance.

18. Buy a USB power filter and ground breaking device such as the IFI USB Power. And since the provided wall wart is noisy, get another linear power supply to replace it instead (next bullet).

• iFi-audio iUSB

19. Buy another simple linear power supply to replace the 9V wall-wart that comes with the IFI USB Power, for example:

• HY1503C Variable Linear DC Power Supply, Analog Display

20. Buy another simple linear power supply to replace the 12V/3Amp wall-wart that comes with the external Thunderbolt Harddrive for example:

• HY1503C Variable Linear DC Power Supply, Analog Display

• Keces DC-116 (2x 3Amp setting)

21. I wanted to replace all the wall-warts, which included the Ethernet switch. Get a metal Ethernet switch like the Netgear GS series as it shields EMI/RFI better than the plastic ones. Buy another simple linear power supply to replace the 12V/1A wall-wart that comes with the Ethernet switch, for example:

• HY1503C Variable Linear DC Power Supply, Analog Display

22. You can go to an electrical store to purchase the cabling and plugs for all the linear power supply replacements. Cheap! Just takes a bit of time and patience in the soldering and DIY department.

23. Buy a USB to SPDIF converter, and have an XLR (AES/EBU) connection to your DAC. Physical distance of anything USB from the sensitive DAC, analog sections and clock is key. There is a reason why Berkeley Audio Design separated out the USB section in a separate box from their DAC. The best, albeit expensive, one I have come across is the Berkeley Audio USB Alpha. I also prefer the XLR as opposed to the RCA connections for noise cancelling.

• Berkeley Audio Design Product

24. There is a bunch of OS tweaking that is needed too, but there are other threads for those. Do it all. I also went as far as removing LaunchAgents and Daemons from starting and running in the background, but be careful here. A bit of trial and error. Copy them into another folder before removing them just in case.

25. A very important piece for me was physical distance between the entire ‘noisy’ computer, harddrive and linear power supply units and the analog gear and amps. I stuck all that in a closet. This way the EMI fields are far away from sensitive gear (this includes your ears), and any fan and harddrive noise (which gets pretty irritating) is locked away. Put at least 1 meter in between the linear power supplies and the computer to keep it away from the magnetic fields. I also have a power conditioner where all the linear power supplies are plugged into.

26. Also don’t forget that if you also watch TV in the same room, replace wall-warts from e.g. your cable provider’s box/DVR (noisy as hell!) and stick the DVR in a closet as well. Get a simple IR repeater USB cable for the remote control.

27. Physical distance between cables is also key. HDMI is very noisy (make sure to get a heavily shielded one as well as use distance), power cables if not shielded (I am all about shielded versions) have a big magnetic field and should be kept well away from analog cables, USB is noisy, make sure to get a shielded one and keep it away from anything analog.

28. Anti-Vibration feet for under the Mac, harddrives and linear power supplies. I grabbed a few cheap Vibrapods that can be had from:

• Music Direct or Elusive Disc online retailers

By the way, all these changes are not about changing the bits of the WAV/AIFF files, as these remain unaltered all the way to the DAC by all of this, but rather it is about removing as much common mode noise as possible, which rides along the cables or is picked up on the way. Whether this is sourced from EMI (electrical and magnetic), RFI, computer, Ethernet connection further upstream, your neighbours light dimmer switch, or even picked up by the cables acting as antennae from unit to unit. Every bit of reduction helps.

Some Noise Sniffing Tools

For those that need a bit of help in determining where a potential problem lies which can be impacting sound or your noise-floor, here are a few simple tools that really helped me, without having the knowledge and skills to use an oscilloscope.

All you need to do to see/hear how much noise is thrown into your listening experience is to run a cheap am radio (try different frequencies) over anything, your cables, cable connections, HD, TV (that is why I turn the TV off, not even in standby, when listening to music), computer, wall-warts. Run it over your laptop power supply block or any wall-wart for shits and giggles, and you will hear squealing. You can use something like a Grundig m400 but any AM radio should do the trick. This one helps in justifying a linear power supply over a switching power supply or wall wart that is on the same electrical circuit/fuse as your audio equipment. I have removed any dimmer and wall-warts from the same electrical circuit. Although some noise might still travel up the ground/earth connection from even your neighbours, but that is for a different thread.

1. AM Radio

• Amazon.com : Grundig Mini GM400 Super Compact AM/FM Shortwave Radio with Digital Display - Black (NGM400B) : Grundig Portable Radio : Electronics

Yet another check is hearing how much noise, for example, a switching power supply throws back into your power lines, and then up into your analog equipment, is to use the Audioprism noise sniffer in a socket next to the one (or on the same fuse circuit) your computer or wall-wart is plugged in. Anything that is not 60Hz will be heard as noise (not sure how high it goes in frequencies though) Try it also with a light dimmer on and off and be amazed/shocked. Use this to check the effectiveness of your power conditioner, as it should be dead silent when the power conditioner works. Some conditioners, even pricey ones, are bollocks.

2. Audio Prism Noise Sniffer

• Welcome to AudioPrism Noise Sniffer

If you want a tool to check EMI (Both Magnetic and Electric) and RFI pollution, get one of these Trifield 100XE meters. These really help in determining how far you need to physically place cables away from each other, or how far the magnetic fields of power cables, linear power supplies reach to help in setting up the distance between your toys. Or it can help in determining what power cord to buy in the first place. Some power cords, even pricey ones, have shite shielding.

By the way, and granted this may seem a bit crazy, but your cooking store will sell oven cookie sheets that are two layers of aluminium compound with air locked inside. Stack two of these on top of each other and use the meter to see how much the EMI is reduced. It was surprising to me. Use it for example for additional separation of the harddrives and the MacMini or stick it under your DAC, if there is a power amp nearby. Very cheap and effective tweak to put underneath your equipment. Other tweaky things are ERS Cloth (essentially creating a Faraday cage effect) and Shakti stones (RFI), but these might be harder to measure or justify. But if it does not hurt…

3. Trifield 100XE EMF Meter

Amazon.com: Trifield 100XE EMF Meter: Home Improvement

Enjoy! Cheers.

Whoa, mama ... I was just about to replace switch psu & hd in a couple of days ... which is merely about 10% of above!

Whoa, mama ... I was just about to replace switch psu & hd in a couple of days ... which is merely about 10% of above!

Don't worry your 10% is 90% of the improvement.

What about some pictures? We love pics!

What about some pictures? We love pics!

Sorry, I did not take pictures along the way. The iFixit website has all the pictures you would need though.

Don't worry your 10% is 90% of the improvement.

Probably true. It is hard for me to assign percentages to which tweak helped by what %. There were a couple that were surprising though, but should not have been I guess. The USB and Ethernet filters were big ones as was the physical spacing. Powering the fan from an external source was a good change too. The last one can be easily tested by unplugging the fan temporarily. Be careful to put some other fan on it in the mean time as you do not want to cook your CPU.

I know it is an insane list, but hopefully at least some of it will help folks optimize their Mac Mini.

Cheers.

Probably true. It is hard for me to assign percentages to which tweak helped by what %. There were a couple that were surprising though, but should not have been I guess. The USB and Ethernet filters were big ones as was the physical spacing. Powering the fan from an external source was a good change too. The last one can be easily tested by unplugging the fan temporarily. Be careful to put some other fan on it in the mean time as you do not want to cook your CPU.

 

I know it is an insane list, but hopefully at least some of it will help folks optimize their Mac Mini.

 

Cheers.

Nice write-up Tranz....Thanks!

Hi Tranz,

Are you using Async USB?

I saw a writeup on the IFi by Darko - he claims that with Async USB combined with the iFi iUSB, one can use an unmodified Mac Mini and get top performance

As far as I know, there are 5 possible noise corruption mechanisms that I am aware of:

1) The USB clock

2) Noise injected through the USB power lines

3) Ground loops along USB

4) USB bit corruption

5) computer noise injected into your power grid, and getting into the preamp, DAC, etc

Some solutions for these are the following:

1) Let DAC do its own clock by using Async USB

2) use a device like iUSB to clean up USB power

use a shielded/filtering, or two-cable USB cable

use a DAC with galvanic isolation

just making these numbers up, but lets say iUSB provides 40dB isolation, filtering USB cable provides 10dB, and galvanic isolation provides 30dB - - in total there should be more than enough isolation

3) iuSB allows one to lift ground

also, a DAC with galvanic isolation

4) Is USB Bit corruption possible due to switcher noise? Skeptical - one thing to point to is processor would start to quickly choke if bits were getting transferred around with corruption. .

5) Use a filter, use power outlet on another grid, etc

It seems that Async USB, iFi iUSB, and galvanic isolation in DAC are the key things in all this.

Its not clear to me why any of the other changes are necessary beyond this?

(I am open to being educated if I am missing something)

dan92075, I've been reading the same: that a proper isolation in the USB output (just like the one you suggest) avoids the need to make further complex changes to the guts of the Mac Mini besides using SSD and increasing the RAM to 8Gb.

I am curious to hear more opinions or experience results. Particularly what tranz thinks about it since he does seem to know what he's doing and experimented a lot.

Thanks!

Nuno

Yes, I am very curious to hear Tranz's opinions on this topic as well since he has done so many experiments in this area. . .

Dan

dan92075, I've been reading the same: that a proper isolation in the USB output (just like the one you suggest) avoids the need to make further complex changes to the guts of the Mac Mini besides using SSD and increasing the RAM to 8Gb.

 

I am curious to hear more opinions or experience results. Particularly what tranz thinks about it since he does seem to know what he's doing and experimented a lot.

 

Thanks!

Nuno

Computer process audio signal in real time and it's just a square wave.

If noise is introduced it will create harmonic & amplitude distortion that will be embedded in the signal.This is for the theory, from experience the improvement that I had when I switched to a linear PSU in my Mac mini was significant despite the fact that I already had an interface galvanically isolated and 5v LPSU for USB.

Computer process audio signal in real time and it's just a square wave.

If noise is introduced it will create harmonic & amplitude distortion that will be embedded in the signal.This is for the theory, from experience the improvement that I had when I switched to a linear PSU in my Mac mini was significant despite the fact that I already had an interface galvanically isolated and 5v LPSU for USB.

Thanks for your comments, alfe.

What kind of USB are you using the 5V LPSU with? Is it an iFi or a SOTM card?

As far as theory - in a strict sense, the computer processing is all digital and analog noise is completely irrelevant to the digital signals - there is no possibility of corruption on that front

So its fascinating you are hearing significant improvements - I am wondering if its due to ground loops from the SMPS making its way through the USB ground, or maybe the SMPS noise is going into the power grid, or maybe the big inductor in the SMPS is magnetically coupling to the big inductor in your DAC if they are in close proximity?

Sorry - I am an engineer - so I always drive myself nuts trying to understand things to the last detail!

But thank you very much for you input on this - by the way - what linear PSU did you end up using?

Thanks for your comments, alfe.

What kind of USB are you using the 5V LPSU with? Is it an iFi or a SOTM card?

 

As far as theory - in a strict sense, the computer processing is all digital and analog noise is completely irrelevant to the digital signals - there is no possibility of corruption on that front

 

So its fascinating you are hearing significant improvements - I am wondering if its due to ground loops from the SMPS making its way through the USB ground, or maybe the SMPS noise is going into the power grid, or maybe the big inductor in the SMPS is magnetically coupling to the big inductor in your DAC if they are in close proximity?

 

Sorry - I am an engineer - so I always drive myself nuts trying to understand things to the last detail!

 

But thank you very much for you input on this - by the way - what linear PSU did you end up using?

I'm engineer too and I'm in bed with digital since 25 years, that's why I never use the expression "no possibility" ¨-)

I'm using a Clones Audio PSU for the Mac mini and AQVOX LPSU for the 5v.

My problem

Thanks Alfe - yes no possibility was a bit strong of a statement - but I guess if all other processing is successful on a computer - your word processing is not getting corrupted - your video processing is not losing pixels - then its highly unlikely that the audio processing is losing bits. Anything is possible though

As far as the AQVOX LPSU - I see its only works on USB power.

Did you ever have a chance to try out an iFi?

I am asking because iFi regenerates/isolates any noise on the digital lines as well, and in addition can also isolate ground.

It would be interesting to see if you use an iFi if you could have an additional improvement?

Thanks Alfe - yes no possibility was a bit strong of a statement - but I guess if all other processing is successful on a computer - your word processing is not getting corrupted - your video processing is not losing pixels - then its highly unlikely that the audio processing is losing bits. Anything is possible though

 

As far as the AQVOX LPSU - I see its only works on USB power.

Did you ever have a chance to try out an iFi?

I am asking because iFi regenerates/isolates any noise on the digital lines as well, and in addition can also isolate ground.

It would be interesting to see if you use an iFi if you could have an additional improvement?

Never had the chance to try IFI .

I will order one and keep you informed.

Never had the chance to try IFI .

I will order one and keep you informed.

Thats Alfe! Hoping it will provide you some benefits. .

Yes, definitely got a substantial kick up in sonic quality with addition of ssd & lpsu to macmini. Next, ... I'm using fw into mytek dac, so further improvement is with ext hd usb connects to mini. Which way to go - just use aqvox 5v or go with iFi solution. What about small usb hds that utilise mini usb power, no wallwarts? Or ...?

Yes, I am very curious to hear Tranz's opinions on this topic as well since he has done so many experiments in this area. . .

 

Dan

Not sure exactly why, as I do not have the skills to check on an oscilloscope nor an EE degree, but my thoughts are similar to what Alfe mentioned. My guess is that if you stick an oscilloscope at the output of your DAC and muckabout upstream, that it will register. There is a youtube video of an EE checking how good his linear power supply was, and found that the neon light and wall warts were clearly impacting the output of the LPSU!

It was not until the Asynch Berkeley USB-SPDIF that I moved from a PCIe based to a USB based server because before it was just too painful to my ears. And even then adding an IFI USB Power on top of the Berkeley helped. My guess is that Berkeley uses an xmos board, reclocking and galvanic isolation as well, but sending the cleaner 5v and cutting the ground via the IFI made a difference. And still, changing bits in the computer helped further reduction in listening fatigue. The fan was a good example where it took me by surprise when having unplugged it.

Likely any time current draws change, whether it is the CPU working harder when other programs are running in the background, or harddrives and fan rpm drawing continuously changing power, it potentially affects the electrical signals going downstream. And since audio signals are real time electrical signals it would seem logical that shite will travel along with it. Much of this might be >20kHz and thus not necessarily heard as audible noise but more a feeling of discomfort/fatigue and masking of spatial cues, a.k.a. raising the noise floor.

There are a few more tweaks I am looking into based on other listeners' suggestions, the first two of which likely make the CAPS pc still sound better.

1. powering the HD externally (not sure how to do this on a macmini)

2. powering the USB pcb board externally (not sure how to do this on a macmini)

3. Adding a balanced power conditioner so that the ground connection is also 'filtered' (equi=tech, bpt or furman 15i). Non-balanced power conditioners will not help shite traveling up ground/earth connections of your system.

Cheers.

Yes, definitely got a substantial kick up in sonic quality with addition of ssd & lpsu to macmini. Next, ... I'm using fw into mytek dac, so further improvement is with ext hd usb connects to mini. Which way to go - just use aqvox 5v or go with iFi solution. What about small usb hds that utilise mini usb power, no wallwarts? Or ...?

Sweet. Since you are using firewire for the DAC, a USB drive should be fine, and most of those come with a wallwart. Run an AM radio over the wallwart and check the noise. Although likely cleaner, the IFI wall wart also squeals and I replaced it. A bit nutty, I know.

Thats Alfe! Hoping it will provide you some benefits. .

I managed to get an IFI today from my audio dealer ¨-)

No benefit compare to AQVOX even slight loss of dynamic.

May be due to the filter in the IFI ?

This is a first impression I will do some more test.

The fan was a good example where it took me by surprise when having unplugged it.

I agree with you Tranz .

I'm using this external fan:

NF-S12A ULN Ultra Low Noise 120mm Cooling Fan, 600/800 RPM

Sweet. Since you are using firewire for the DAC, a USB drive should be fine, and most of those come with a wallwart. Run an AM radio over the wallwart and check the noise. Although likely cleaner, the IFI wall wart also squeals and I replaced it. A bit nutty, I know.

The iFI guys assert differently:

Detailed analysis:

For 100Hz noise the generic SMPS produces around 40dB or 100 times more noise than the iFi ULN Adapter. At the main switching frequency the generic SMPS had nearly 100mV switching noise, while the iFi ULN Adapter has less than 300uV, a 300 fold improvement for the iFi ULN Adapter!

Even the expensive dedicated low-noise linear regulated power supply has more noise than the iFi ULN Adapter at most frequencies. We see as much as 20dB/10 times more noise around 100Hz and in the 5kHz – 30kHz range from the linear supply! But we can also see that the linear supply is a significant improvement on the cheap generic SMPS.

The next time you listen one of iFi’s product and remark how quiet it is, don’t forget to thank that little unassuming iFi ULN Adapter!

Audio Precision Series 2 Test System - to measure is to know

All tests were carried out under identical conditions and used our Audio Precision Series 2 Test System. This test system, with an MSRP of USD19,250, is an industry reference standard and used widely in the industry as well as by Stereophile and other magazines for audio measurements. All power supplies were tested with 15 Ohm loads, which for 5V supplies mean 333mA current where drawn while for 9V (like our iFi ULN Adapter) the current draw was 0.6A.

What about some pictures? We love pics!

I managed to get an IFI today from my audio dealer ¨-)

No benefit compare to AQVOX even slight loss of dynamic.

May be due to the filter in the IFI ?

This is a first impression I will do some more test.

That was my very first impression too - a slight loss of dynamics.

However, later what was eye opening for me was when I was able to resolve details in familiar tracks that I had never heard before.

I then began to realize that the slight "loss" of dynamics was due to noise riding on top of the peaks. I realized I was used to an extra fizz on the peaks which was giving a fall sense of dynamics.

As I began to enjoy the extra detail and texture it now sounds wrong to me when I go back to the noisy case.

Let me know if you come to that conclusion to - or if you still think there is loss of dynamics?

That was my very first impression too - a slight loss of dynamics.

 

However, later what was eye opening for me was when I was able to resolve details in familiar tracks that I had never heard before.

 

I then began to realize that the slight "loss" of dynamics was due to noise riding on top of the peaks. I realized I was used to an extra fizz on the peaks which was giving a fall sense of dynamics.

 

As I began to enjoy the extra detail and texture it now sounds wrong to me when I go back to the noisy case.

 

Let me know if you come to that conclusion to - or if you still think there is loss of dynamics?

After extensive listening session using the M2 tech evo stack I will give a subtle advantage to the AQVOX (better dynamic not noise ¨-)), in the other hand when I did the test with the Stello U3 the IFI sounded better.

I think the choice between the two is depending on the interface galvanic isolation.