Is USB straight from a Mac computer to a DAC really that bad?

[davide256]

On 5/29/2020 at 5:08 PM, audiophile911 said:

Is USB straight from a computer to a DAC really a bad or should everyone always strive to isolate the computer's USB output from the audio stream???  I connect my Chord Quest directly to my Mac Mini; which is dedicated to only running ROON Core; with an AudioQuest Diamond USB and I think it sounds great.  But I according to manufactures of network streamers, eliminating the computer (or using an expensive audio optimized PC like an Innuos) will always sound significantly better.  I've also read that this is not necessarily the case and it really depends on how usb is implemented in the source and the DAC?  Specifically, I heard from Rob Watts of Chord explain that Chord DAC's are optimized for USB direct input.  So, I'm trying to decide if I need to try something like a SOTM SMS-200 Ultra or a Sonore UltraRendu but I'm hesitant to go to the expense and hassle of more boxes.   I recently read this update on this $150K system: https://www.soundstagehifi.com/index.php/opinion/1392-after-25-years-is-this-the-worlds-best-audio-system  Specifically:

"Some Facebook readers criticized me for not using an audiophile-grade music server or USB link. I responded that if anyone can show me a music server or USB link that actually sounds better that what I have in terms of resolution, tonality, soundstaging, imaging, whatever -- I’m all ears. But so far, I’ve heard nothing that has proven itself better-sounding or more versatile -- my computer plays any digital music format and file type from streaming services and my local music drive, and my USB link, with its lengthy length, transfers the bits just fine.

The reason I can get away with using a laptop has to do with the next component in the signal chain: the EMM Labs DA2 Reference DAC ($25,000). Designed by Ed Meitner, who’s been creating digital-audio products since the 1970s, the DA2 Reference seems immune to swaps of USB links, as well as differences in source components."

 

Am I missing something??

I'd say that based on my experience the author of your quote is about 4 years behind the times in computer audio source experimentation... no DAC can fix what the source has damaged at USB output

 

An apple laptop can come close to the original 1.3 microRendu for USB out. But there are far better options now using 3 variables

1) NAS streaming

2) upgraded power supply

3) OS & apps running in memory or off memory like disk, no SSD/HD in the endpoint

[davide256]

49 minutes ago, beerandmusic said:

 

I have heard this before, but I am not sure I believe it.  Most everyone agrees that the dac gets the digital bits perfectly, it's just that there is noise.  So if the DAC implementation is well, and it can get the bits accurately, why can't it regenerate the bits "that it gets perfectly", and then provide it's own 5v.  In theory, this should be a good implementation, and also what the unsion usb markets?  I would think that every "good" dac should do this by this generation of dacs?

time flows backwards for no one. While DAC's matter they can't make a bad source good.... if its error-ed in hand off to USB out, its too late.

Cheaper digital sources remind me very much of cheaper vinyl TT's, compressed dynamics and blurry for background details.

[davide256]

8 hours ago, beerandmusic said:

 

You may not be able to make a bad source good but let's think about what we are saying.

A bad source can be a bad recording, but that is not what i am speaking about.

 

Let's start with the bits on the media are perfect as proven by checksum.

 

Exiting the source, you have the perfect bits and call it noise.

Assuming music = perfect bits + noise and nothing else.

 

We know the dac gets the perfect bits.

 

The dac conversion of course will be different based on the dac engineering, but right now, all we are trying to deal with is the input.

We already know they get the bits perfectly.

 

Are we together so far?

 

 DAC's reproduce/flow control what the USB chip sends them. They have no influence over what happens before the USB chip. USB just happens to

be the 2nd best problem prone/ closest to internal computer protocols transport solution compared tto coax and toslink. Ethernet is the least problem prone

digital data transport for audio if you have the rare DAC  and software driver to support it. The reason I say its best is because USB is a hybrid digital/analog

signaling method for very short distances, Ethernet is pure digital domain until the Ethernet enabled DAC begins processing data and can be used regardless

of distance between source and DAC

 

What you miss is that endpoint computer hardware and software integration are key. Computer audio is easily degraded between disk read and

hand off to the DAC output by software and hardware. Apple doesn't have any better a USB port than anyone else... but they control

completely the software and hardware integration which as a byproduct means that most Apple computers do audio acceptably well vs the crap shoot

with an off the shelf windows PC. Likewise NUC's as an Intel controlled product do well. But more is always possible, Apple and Intel both have to make machines

that are general purpose vs solely designed/optimized for audio.

[davide256]

6 hours ago, beerandmusic said:

 

Do you agree that the only thing that is sent from the usb to the dac is:

a) digital music (most everyone agrees that this digital data is received accurately)

b) reference voltage

c) noise

Do you agree that the fuel pump on your car sends gas? And if so do you disagree that a fuel pump doesn’t behave any differently whether the gas is good or poor? That’s all asynch USB is, a “fuel pump” for the DAC that doesn’t care or know how good or bad it’s source is

[davide256]

22 hours ago, AudioDoctor said:

Interestingly, my new DAC has a Roon Bridge built in, however I find the sound to be better coming from the USB output of a Sonore Signature Rendu SE via Roon and HQPlayer than using the Roon Bridge directly.

Yup, wrong direction to bring a specific software vendor's player implementation inside the DAC. A real ethernet DAC implementation should look very little different than a wired DAC

beyond having an IP address and a device driver based on IP, similar to attaching a remote printer and available to any program able to use the sound  device driver.

[davide256]

3 hours ago, beerandmusic said:

comparing good or bad gas would be more like comparing one song to another, and besides doesn't make sense to compare usb to a fuel pump.  usb always transmits the bits accurately, even if there is noise on the line....if you can get the bits perfectly, a good design should be able to compensate for any noise.

So basically you are arguing that their is no difference between the output presented to USB from the cheapest computer possible to the best possible. Good luck with that approach,

you won't get past the level of sound quality you hear at a Walmart. Software, hardware and power supply do matter.

[davide256]

4 hours ago, beerandmusic said:

 

iimproved timing is likely needed for upsampled DSD rates which is not at least what i am looking for.

 

I just want to know if a technology such as unsion that includes isolation and regeneration is sufficient without getting into the debate of high-res which i consider a totally different topic, that i have my own and separate debate about.

Mehh, Unison is just an incremental improvement over Gen 5. I'm moving on.

[davide256]

5 hours ago, 6aardvark9 said:

 

I thought it relevant, since the (reclocked/improved) timing of the digital signal makes a difference, even with high(er) end DACs

Mojo's not exactly a higher end DAC but ratcheting up the source data rate to max PCM or DSD rates sure improves clarity of CD quality recordings.

[davide256]

1 minute ago, beerandmusic said:

 

No, I am not arguing there is no difference, I am questioning the logic and reasoning.  You would think a DAC engineer would be able to provide a "logical" explanation...but even DAC engineers shrug like they do not know why.

 

Keeping in sight these basic principles.

 

The only thing transferred to the dac from the pc are:

1. Digital bits (which everyone agrees the DAC receives with 100% accuracy)

2. A reference voltage

3. Noise

 

4. If you take into consideration that the DAC receives its bits with 100% accuracy and that the PC's reference voltage should have no impact since it is isolated from the DAC's Design.

 

5. If you take into consideration that the DAC has it's own reclocking/regeneration of the bits that it recieves with 100% accuracy, then the PC should not make any difference.

 

A different dac may make a difference, but a different pc should not make a difference if you accept 1-5.  If you don't accept 1-5, then which don't you accept and why?

 

Again, not comparing DAC A to DAC B, comparing using different pc's with same DAC.

 

DAC engineers would consider anything before the USB output as "someone else's black box"... they don't get paid to solve someone else's problems.

A software engineer for a computer audio program might be a better place to start... they could give you a sampling of technology reasons why current computer audio

is not "the best of all possible worlds"

[davide256]

1 hour ago, beerandmusic said:

 

Any software engineer (or hardware engineer) would state what I have...that the bits are transferred perfectly along with a reference voltage and noise.  I am not referencing potential issues with upsampling. 

Actually they would be mystified as to why you are reducing  a layer 7 application level problem to just a  layer 2 link level problem... assuming they were educated  in computer technology and data transmission. Which is definitely not the skill set of a DAC engineer.

[davide256]

21 minutes ago, beerandmusic said:

 

I am not going to read the entire article, but if you want to share what are the line(s) that state what the resulting sound will be in the case of loss bits, i will entertain the thought?

 

This discussion came up many times, and i used to be on the other side of the thinking...but it seemed all/most of the audio engineers here agreed that the bits are received correctly and when not, it just caused a glitch.

 

 

 

 

 

you need to stop spouting BS. What you mean is the engineers you want to agree with in the objective camp are spouting this... not the engineers who are actually exploring and selling products that aren't limited to midfi level of fidelity

[davide256]

9 hours ago, beerandmusic said:

 

I don't want to agree with one side of the camp or the other.  I am unbiased, and just want the facts.

Two years ago, i started this a topic with this same thinking...

============================================================

As a matter of fact, here is an exact quote of mine from 2 years ago:::

 

I accept noise of all types affect SQ, but everyone kept suggesting that the DAC gets the music bits perfectly, but that noise affects the dac in processing.  This suggests that the DAC doesn't even receive the music bits with accuracy due to noise....big difference.  Some suggest that dacs can resolve for most noise, that's all dandy, but if the music is already inaccurate before it gets to the DAC input pin(s), there is no way to fix it at that point, if it is already corrupted.

===========================================================

The topic ended with basically no one agreeing with me or IFI....that bits lost are either SO RARE and even if they do happen it would cause a dropout, not a difference in SQ....but if people think differently today, that certainly goes along more with what I find logical.

 

If you want not to be years behind in where computer audio has gone, you need to devote a weekend to reading the thread below. A lot of research by many different CA members with converging results and some key findings linked/ summarized up front. I ignored it in 2017-18 only to find out I had spent time and money duplicating results/conclusions already reached

in the thread and needed to catch up.

 

 

[davide256]

4 minutes ago, The Computer Audiophile said:

In my experience jitter can round the edges of transients and make music sound soft. 

hmm, that sounds much like what more modest tube gear does. Which some actually like... probably a necessity if you still have use Koss 1 electrostatic speakers

 

7 minutes ago, 6aardvark9 said:

 

Quite the opposite for me... I consider jitter to cause digital glare and top end harshness

tended to find this linked more to source hardware and power supply quality. Of course a PS Audio Dlink III could make any source sound like that

 

what I've experienced is that timing degradation in the source causes background instruments to lose definition

[davide256]

30 minutes ago, beerandmusic said:

 

This is what i always test for.  The track by Chet Baker "ALONE" is the "PERFECT" test track.

Depending on different solutions I have tried, there is a very light instrument in the right speaker, that is either clear, extremely faint, or non-existent.  I finally hear it vividly now using unison out my every day windows PC that has been absent in past, that i could always hear when streaming or via a usb thumbdrive.

 

mm, I'd use that that as a warmup exercise but not challenging enough to be a test for me. I do like Chet though.

 

Its not a high quality recording but I  like the Jurassic Park II sound track for interesting background details... the tympani  parts are very telling on whether you are reproducing

tympani authentically.

 

 

[davide256]

1 hour ago, audiobomber said:

The main timing degradation for me is poor PRaT. I had a CD transport and DAC with separate clock link. Disconnecting the clock link caused no difference in tonality, but the music became boring. Instead of being riveted to the music, my attention wandered. No boogie factor, or in Linn terms, no foot-tapping.

 

this digitally restored 1911 film probably falls along the same lines... the closer something is to what your senses normally experience, the more real it is to you

 

 

 

[davide256]

1 hour ago, beerandmusic said:

I just looked at your system details and it says gungnir mb unison...i thought you said you used a mojo, or am i mixing you up with someone else?

in transition. selling Gungnir, mojo is interim solution enroute to Qutest.

[davide256]

1 hour ago, beerandmusic said:

 

out of curiosity, how do you play this jurrassic park ii soundtrack? from youtube like the ny scene you shared?

Qobuz. looses some cymbal and low base definition compared to when I compare same recordings on NAS but still very good. An iPhone and Qobuz makes

DAP's seem cost ineffective.

[davide256]

Mac notebooks are still very commonly used for demos at audio shows... you can do better but its more likely without research to do far worse.