USB sucks


USB really isn‘t the right connection between DAC and Server: depending on cables used, you get very different sound quality if the server manages to recognise the DAC at all. Some time ago I replaced my highly tuned Mac Mini (by now-defunct Mach2mini, running Puremusic via USB) with an Innuos Zenith Mk3. For starters I couldn‘t get the DAC (Antelope Zodiac Gold) and server to recognise each other, transmission from the server under USB2.0 wasn‘t possible because the server is Linux based (mind, both alledgedly support the USB2.0 standard) and when I finally got them to talk to each other (by using Artisansilvercables (pure silver) the sound quality was ho-hum. While I understand the conceptual attraction to have the master clock near the converter under asynchronous USB, the connection‘s vagaries (need for exact 90 Ohms impedance, proneness to IFR interference, need to properly shield the 5v power line, short cable runs) makes one wonder, why one wouldn‘t do better to update I2S or S/PDIF or at the higher end use AES/EBU. After more than 20 years of digital playback, the wide variety of outcomes from minor changes seems unacceptable.

Since then and after a lot of playing around I have replaced the silver cables by Uptone USPCB rigid connectors, inserted an Intona Isolator 2.0 and Schiit EITR converting USB to S/PDIF. Connection to the DAC is via Acoustic Revive DSIX powered by a Kingrex LPS.

The amount of back and forth to make all this work is mindboggling, depending on choice of USB cables (with and without separate 5V connection, short, thick and God-knows what else) is hard to believe for something called a standard interface and the differences in sound quality make any review of USB products arbitrary verging on meaningless.

Obviously S/PDIF gives you no native PCM or DSD but, hey, most recordings still are redbook, anyway.
Conversely it is plug and play although quality of the cable still matters but finally it got me the sound quality I was looking for. It may not be the future but nor should USB, given all the shortcomings. Why is the industry promoting a standard that clearly isn‘t fit for purpose?

Finally, I invite the Bits-are-bits naysayers to go on a similar journey, it just might prove to be educational.
antigrunge2
@herman 

Since you like the Antelope DAC: may I suggest you try it on S/PDIF or AES/EBU? With the Schiit EITR the sound is far superior to USB all the way through. And by the bye: the Intona substantially improves the straight USB connection compared to a split lead all silver USB cable. I believe that the effects of noise (either from 5v leakage from the server or all sorts of airborne grunge) on the DAC’s receiver implementation and clocking is still not well understood.
@herman  As a programmer and electronic interface design engineer, you're not "locked" into using isochronous mode: You have bandwidth and buffers so if i can transfer 500 MBps+ (using SATA SSD = 4 Gbps+) of data without error (well, if there are errors, they are corrected), it should't be a problem to playback music!

The USB spec has a enough protocol sophistication to handle many things.  Of course, computer setup, minimal cabling care (lenght, compliance, etc) and other evidences must be met.

Want to test cables for performance?

https://www.passmark.com/downloads/USB3LoopbackPlugUsersGuide.pdf
It's about 100$ so for those who want to spend big money on cables, that shouldn't be a problem.
On the Linux platform, you can hook to the kernel and you have a rich set entry points / data to monitor USB for performance and errors.  Windows / Mac should have a couple of tools too (i'm a Linux user, so not sure about those 2).  So imagine testing a USB cable with NVMe to USB adaptor and pushing gigabits of data through it.  If your cable is not good, it'll show.

cp /dev/nvme0n1 /dev/null

(copy from external NVMe USB drive to NULL = Max Speed of the source).  Of course it's bulk mode!


As for transfer mode, here is a user question and a response from usb.org:

https://thepenguin.eu/2018-01-19-audiophile-usb-cables/

USB transmits information digitally. Bits are either received correctly or not received. What a bit looks like on the wire has no effect on quality if the bit is received correctly. If a bit is not receive correctly, error checking in USB protocols will flag the error in data transmission. Jitter is not a cable problem. Jitter is a transceiver (PHY) issue on the devices. Can bits get scrambled within a cable assembly on occasion? Yes, primarily due to EMI but this is highly unlikely -- more on that later. Is occasional data scrambling a problem for audio/video?
Maybe. The answer depends on the hardware receiving/rendering the data. USB supports isochronous transport which is a timely delivery of data. The isochronous transport has guaranteed bandwidth on USB. Isochronous protocol, however, does not support error recovery. In other words, if data is flagged as an error by the receiver, there will be no attempt at data retransmission.
So if the receiver is using the isochronous protocol, then there can be errors in data. Most webcams use the isochronous transport. High-end audio/video equipment that does not mandate real-time delivery of data should not use the isochronous transport because accurate data delivery is not guaranteed.
USB also supports bulk transport. The Bulk transport shares bandwidth and timely delivery is not guaranteed. Bulk protocol does have error recovery and errors in data will be retried. If the receiver uses the bulk USB protocol, then there will be no errors in the data.
This is why USB mass storage devices always use the Bulk transport. Most USB audio/video devices use the bulk transport because real-time delivery of the data is not necessary. Bulk audio/video devices will buffer data before rendering it.
I can think of only two situations where the audio/video will be disturbed when rendered: 1) If the host is busy performing IO to other USB devices, or 2) There are errors in data transmission where continual retries cause buffer under-run to occur.
The second point could be cable related -- it could also be poor hardware design of the host or peripheral as well. The USB Bulk transport works very nicely for audio and video because data is accurately delivered. Now onto cable quality. A cheap USB cable will work perfectly fine in the vast majority of home/office environments. All USB certified cables use certified connectors and are shielded, have minimal skew on the data lines, and meet criteria regarding impedance and voltage drop. If the environment is extremely noisy with EMI, then a better shielded cable may be necessary. Usually relocating the cable or power strips will suffice to mitigate EMI. Personally, I would never recommend anyone buy an expensive USB cable unless they are experiencing problems not related to their hardware and there exists definitive suspicions of environmental interference.
I do always recommend that the cable purchased be USB certified which provides assurance that the product is properly designed for USB. Using USB certified audio/video equipment also assures that the USB signal quality and other packet parameters of the transceiver meets specifications. Of course, all of the above is premised upon properly designed and functioning hardware. Regards, Mark Paxson USB-IF Compliance Administrator [email protected]


Most USB audio/video devices use the bulk transport because real-time delivery of the data is not necessary.
This simply is not true if "most" includes the topic at hand... USB DACs? 

 As a programmer and electronic interface design engineer, you're not "locked" into using isochronous mode: You have bandwidth and buffers so if i can transfer 500 MBps+ (using SATA SSD = 4 Gbps+) of data without error (well, if there are errors, they are corrected), it should't be a problem to playback music!

It doesn't matter what could be done. It matters what is done, and since asynchronous is what is done, errors are not corrected. End of story.
@antigrunge2 

Since you like the Antelope DAC: may I suggest you try it on S/PDIF or AES/EBU?

fair enough, but how do you generate the signals? There are a few ways I know of, Ethernet to spdif with a

  • Raspberry Pi HifiBerry seems like a step back, maybe not
  •  DCS network bridge, $3500 , more than I paid for the Antelope
  • $20K+ Aurender W20, not an option for me

Of course there are USB to spdif but we are trying to eliminate USB. 

suggestions ??

Far from having ‘dissolved itself‘ I sincerely hope that this thread might lead serious designers to reconsider whether rather than using a low end, convenience consumer interface with all its known foibles to transmit high quality audio, one might usefully revisit more appropriate formats (optical, I2S, AES/EBU) to improve on what is at best an unacceptably wide range of outcomes with USB; I also note with a degree of puzzlement that members of the ‘bits are bits’ school of sitting on your ears are alive and well

Respectfully, it kinda has.  Its' just another "I'm right you're wrong" (not directed at you).  Armchair experts everywhere.

Its fine to not like USB, or.......but keep in mind it's an individual use case.  This thread isn't going to change a designers mind to all of a sudden say, "hmm someone on the web doesn't like USB, I should probably use spdif"
The amount of info with issues, aka " with all its known foibles" on every interface is easily documented / found.  i2s, AES etc.. ALL have (potential) issues/shortcomings, given how its implemented in certain products.  It's either done right or not.  Again, implementation has been repeated ad nauseam.  That's the bottom line on how I see it.

I'm not trying to change anyone's mind, why would I care, whatever floats your boat.   Everyone's use case (which is pretty critical in the overall scheme of things) is different and It's really about having a mature discussion. 


I beg to differ Schiit Audio New unison usb is even better then Bnc,or Spidif 
I compared several cables in the $500 range and even less the  Unison USB
card was clearly more resolved and natural sounding .this new card does take around 200 hours to fully runin .
but is an advancement over Xmos 
or others multi function processing models .this being proprietary and only does 1 function ,and does it well. 
I just dropped my cartridge needle down onto my vinyl record or put my CD into my CD player and hit play and I get great music and nothing to worry about
I just dropped my cartridge needle down onto my vinyl record or put my CD into my CD player and hit play and I get great music and nothing to worry about

hey grandpa.. check the date on your flip phone, it is 2020

I have discovered such a tremendous amount of new to me music and new artists since going with Roon, Tidal, and Qobuz that I can’t imagine being locked into the extremely limited number of choices my personal collection allows, and that is in the thousands, I hear amazing things every day that I never knew existed. For less than the equivalent of what I paid for a single CD a month in 1985 I have access to literally millions of songs every day in CD or better quality... MILLIONS !!!!

when I read about an album in a magazine or the web, chances are it is instantly available to me. When I hear an artist I like chances are I have instant access to their entire catalog along with recommendations for those that are similar. It is the golden age for music lovers that are willing to "worry about" how to connect their server to their DAC.

I feel sorry for you if you are limited to physical media listening to the same stuff over and over and over.


I click on my roon app, find an album and hit play. Nothing to worry about. I will add if you're going to use the approach of streaming it's a good idea to understand some basic networking and how digital transport works. Most of the stuff I read on digital threads about reclockers, line filters and cables is nonsense. I use a roon NUC connected to my network and a raspberry pi4 as a bridge to my DAC basic ethernet cat6 cable basic USB cable. Simple easy setup best sound I've ever had good as or better than CD and forget vinyl.
I just returned to civilization from a trip to Yellowstone National Park with my wife on our wedding anniversary. Managed to see my first wild bear, well a mum and three cubs playing in the water together. In my travels I've always said every country has something unique to offer the traveler - America has never disappointed!


@guyboisvert - yeah thanks for sharing, charming really.
I can tell you didn't pass any degree, you should study a bit before trying to look that you know something, you just don't...
Engineering theory is great, congratulations on your studies sir.

Certainly there is a plethora of information more specific to audiophile needs than general computing has been provided in this thread, however it seems that conjecture and opinion varies sufficiently enough, that anyone who actually wants to know for themselves if different devices and or cables with different connectors and materials can more or less effectively change the final resolution of their system,
really aught to try it themselves.

There are enough people in here who claim they have had superior results in their playback systems to merit investigation.

I for one have a system where I can hear payback quality change using different USB cables, interconnects, speaker cables and power cables.
Not sure how relevant my setup is but will throw it out there.
Running Roon core on an old Dell laptop that is stripped bare and that is all it does.
That is connected to my network main router by short ethernet cat8 cable.
Long ethernet cat7 cable goes down to my network switch in music room powered by 5v LPS.
Short cat8 ethernet cable connect to Sonore Ultrarendu bridge fed by 7.5v LPS.
1M Audioquest Carbon USB cable from rendu to Metrum Onyx dac.

SQ?

Off the charts and all instant plug and play, Roon finds everything on my network including the Onyx.
I'll get flamed for this I'm sure.

On the USB A connector, the flatter rectangular one, on the top side I use my thumb to give it a little depression to better "clamp" the conductors against the terminal.

Obviously there is not much one can do for the USB B connector.

Whether or not it improves the signal by adding a little clamping force I dare not conjecture, however I find it gives me peace of mind knowing it's a bit more secure.
I'll get flamed for this I'm sure.
Why?
It sounded perfectly reasonable to myself.
I always wonder about the integrity of that connection, not that I have any proof or comments either way.
If it does not hurt anything then why not?
“I for one have a system where I can hear payback quality change using different USB cables, interconnects, speaker cables and power cables.”

@rixthetrick,

You are not alone, there are many here who appreciates the uptick in SQ from cables and other tweaks. Just ignore the few Debbie Downer’s that are constantly lurking around with their cave man mentality.
@ubrwaltz - most everything I am reading now in forums (I use a PC based platform as a music server) is that Ethernet does resolve better than USB for the purposes of digital audio.

My next DAC purchase is most probably going to use that method in the future. I am however waiting to make my next move in DAC choice to better position myself in return on investment. The improvements are rapidly costing less as the technology develops across the board.
@ lalitk1 - Of course I meant to type PLAYBACK, not payback...
hahaha a Freudian slip ( parapraxis ) perhaps..hahaha
@rixthetrick
Can I suggest you use a whiff of Caig Deoxit on either end rather than resort to brute force?
I did swap out the original fairly cheap Straightwire usb cabLe for the Audioquest Carbon for what I perceived to be a slight uptick in SQ.
The Carbon came free with the UltraRendu so I have zero skin in the game for any financially implied placebo effect imho.
An USB DAC uses async digital transport with buffering. Then, it uses its own accurate internal clock generator to convert the digital data to analog.

So USB clock is not related to quality of sound whatsoever, nor cabling or connectors, etc!
@guyboisvert This all sounds nice on paper, but in real life buffering creates latency, a clock is highly susceptible to any noise that is mixed with the signal ( and there is a lot of such noise created by the motherboard, processor, EMI etc), and this is just the beginning.
We have the whole range of issues here, from the so called common notion of time to parasitic loops. The isochronous transfer used for real-time audio is far from perfect, it is not the same as a bulk protocol used for data. 
Having said that, a USB connection may sound impressively well. Or it may be really noisy, depending on the implementation and many factors. I have a ZEN Mk3 and an Aqua DAC, and the difference between USB cables is significant to say the least. 
@ antigrunge2 - Thank you, I am actually currently looking into technologies that enhances connections. I do agree that oxidization is certainly an area which needs to be addressed in connections, especially for example copper.
Still, there’s nothing wrong with a good mechanical connection, yes that’s personal opinion.

And more totally off topic -
https://www.youtube.com/watch?time_continue=7&v=Y2nQ8isf55s&feature=emb_logo

Imagine if it were possible to have a totally solder free set of cables, or crossovers, amplifier etc. Cold welded USB, XLR cables and speaker cables. Okay enough have eluded to my being in a fantasy world, without my providing evidence.

A good friend just purchased an Auralic Aries G1, which Johnny Darko reviews in the link below. It’s connected via USB, the same brand of USB cables that I used to build.

This may be my next purchase actually - yes it’s still got USB, as well as Toslink, Coaxial, and AES/EBU.

https://www.youtube.com/watch?time_continue=319&v=7bO1RHX3LuQ&feature=emb_logo
I have a ZEN Mk3 and an Aqua DAC, and the difference between USB cables is significant to say the least.

 I am not questioning what you hear. However, it is almost impossible  to believe that an asynchronous USB DAC can't be designed to be immune from any nastiness coming in on the cable. The technology is too mature to accept that a multi-thousand  $$ DAC can't effectively handle a USB input without expensive cables. 

but in real life buffering creates latency, 
Latency is completely  a non issue in home audio. It matters not if the data stream starts now or a second from now. All that matters is proper timing once it starts. 

a clock is highly susceptible to any noise that is mixed with the signal ( and there is a lot of such noise created by the motherboard, processor, EMI etc), and this is just the beginning.

a cable on the input will not have any effect on any noise generated inside the DAC. Any competent designer can filter out any noise coming in on the cable isolating the rest of the DAC from the noise. The idea that the USB cable can be an effective filter  and the DAC input can't isn't reasonable. 

Again, I don't question what you hear, I question the design of a DAC that is affected by USB cables. 
Any competent designer can filter out any noise coming in on the cable isolating the rest of the DAC from the noise.

This is not true, even Nuno Vitorino, the boss and designer of Innuos ZEN admits that if the transport is noisy, it is very difficult and sometimes impossible to filter the noise that is mixed with the audio signal. He openly admits that there are still a lot of unknowns and anyone who is saying the opposite simply doesn’t know what he is talking about. ( Nothing personal here ))

That is why they go to great lengths to prevent the noise occurring in the first place, by using more expensive multiple power supplies, carefully choosing processors and motherboards, trying to prevent ( ha ha) EMI pollution etc.

If that would be so easy, any laptop would be a perfect digital file transport. But what we hear is that a dedicated hi-end server like Innuos is vastly superior. It is so much better, its not even funny. Hell, I have two of their servers, an old Mini Mk 1 (which beats MacMini hands down) and a new ZEN Mk 3, and the difference in SQ is night and day.


The technology is too mature to accept that a multi-thousand $$ DAC can’t effectively handle a USB input without expensive cables.

I did not say that. What I meant was that USB cables can change the sound of a well tuned hi-end system. They "sound" differently, if you wish ))  And a multi-thousand $$ DAC simply can not employ heavy filtering, simply because it kills the sound: adds modulations etc. 
But I like your enthusiasm about new technologies ))) We will get there sooner or later.


This is not true, even Nuno Vitorino, the boss and designer of Innuos ZEN admits that if the transport is noisy, it is very difficult and sometimes impossible to filter the noise that is mixed with the audio signal.

A testimonial from Innouos about the necessity of high end servers is like a testimonial from Elon Musk about electric vehicles. I agree once you mix noise into the audio it may be impossible to eliminate, but there are no audio signals in an Innouos Zen so what is he "admitting". As far as I can see they sell only servers.. no DACS, If I was selling expensive servers, I would also argue that DACs are incapable of filtering out noise so you must buy my server to get rid of it before the signal gets there.

I have tried a pretty good variety of devices and cables listed previously to feed my DAC including a Roon Nucleus on a linear supply and Innouos Zenith MK3 with the Phoenix USB clocker as well as cables compared to my Mac Mini and $50 USB cable. I hear nothing "significantly" different or "vastly superior" about them. As I said earlier, it may be that I have wooden ears or my pro audio interface with reference, internal, re-clocking and jitter reduction handles it better than most. You can check my system and see it should be able to resolve any differences.

In any case I feel very fortunate. I’ve done the experiment so I can sit back and listen to wonderful music without fretting about what I need to do about USB cables and servers and clockers , etc. A recent extensive review on Audiophile Style lauds the superiority of a $26K server that to be optimized needs expensive power conditioning, ethernet re-clockers and ethernet cables with expensive USB cables .......

Ethernet in - USB out does not require $30K+ to optimize. I stand by my position that if your DAC is significantly and vastly improved by a server and/or cable you have a DAC problem.

I also understand the fun in trying it all and the joy (too strong?) of owning them. Have fun


And a multi-thousand $$ DAC simply can not employ heavy filtering, simply because it kills the sound: adds modulations etc.

I was very specific about where the filters are... I said 

Any competent designer can filter out any noise coming in on the cable isolating the rest of the DAC from the noise

so I’m talking about filtering and noise reduction of the incoming digital data stream, not the audio. Cleaning up the data stream will not kill the sound or all of these expensive servers and clockers would kill it too. Filtering noise from the incoming USB digital signal will not modulate anything.
If you're having problems try a Benchmark DAC3.


Benchmark's USB system supports USB Audio 2.0, DSD, and USB Audio 1.1. It is frequency agile, and will follow sample rate changes initiated by the computer and/or the media playback software. In all modes the USB communications are asynchronous in order to eliminate unnecessary sources of jitter.

The DAC3 has a low-jitter master clock which controls the transfer of audio data from the computer to the USB sub-system. The computer asynchronously transfers audio data to a buffer in the DAC3. The contents of the buffer are then asynchronously transferred to the D/A conversion subsystem. This second asynchronous transfer eliminates any traces of jitter that accumulate as the data is transferred between the USB and conversion subsystems. No traces of jitter-induced distortion are measurable to our measurement limits (better than -150 dBFS). This truly represents the state-of-the art. Enjoy the convenience of computer playback without compromise. The Asynchronous USB system supports USB Audio 2.0 for high-resolution 192kHz, and DSD playback. 

So, the OP is saying that the USB connection I have via an iMac computer and a PS Audio sucks, and I should spend a gazillion dollars in an attempt to upgrade the sound?  No thanks, my USB connection is perfect. And the sound is just marvelous. But nice try!
The optimal way to play a digital file has already been found over a decade ago - DLNA enabled or other network enabled streamer with built in DAC. This is essentially a CDP for the modern era. One box fully integrated and optimized solution without dicking around with connectors, wires, connection formats and multitude of other “options” that do nothing but degrade/change sound. 
Post removed 
@lgldsr73 - There's got to be a better way for sure.
If audiophilia were more of a priority for engineers, we might already have it?

I've been present when USB (using a high end USB cable), toslink, and coaxial cables (even high end contenders) have all been put to the test - USB had won. Mind you this was a couple of years ago now, and I acknowledge things change rapidly in our hobby.

There's AES3 aka AES/EBU which looks promising to me, though I haven't tried it personally.

I am disappointed that digital hasn't yet universally beaten the older methods of analogue recording and retrieval. With constant advancement, and new data transfer protocols, newer technologies in processing the digital format to analogue - I hope one day it will.

As I believe camera technology has surpassed film finally. Hasselblad H6D-400C, PhaseOne XF IQ4, Fujifilm GFX 100 are high end examples of this, where digital finally is better than analogue.

What do you think is the best at the moment? What are you using?

Rick
Post removed 
"why is there a significant market for USB clean up and reclocking devices by Uptone, Intona,IFi, Schiit, Berkeley Alpha, InnuOs, Aqua, DCS et al?Are they all selling snake oil?"

I cannot say what others are hearing (or think they are hearing) by adding these devices. I’ve added a couple (from Uptone, Sonore/SGC). When the devices do recognize each other, the SQ is quite good. However, it isn’t necessarily better than the SQ I get from ethernet or S/PDIF. It’s just that I can’t help myself from tinkering with HQPlayer filters and such through USB. For most "normal" people (not OCD audiophiles) this would be a complete non-starter. They do not have the skills/mind-set/patience to go through the trouble-shooting needed to fix a broken USB handshake. Just plug in the ethernet or S/PDIF cable, enjoy the music, and be done. Caveat:  I own pretty good (but not phenomenal) gear and am in my 60s.  Maybe with better gear and ears, I'd notice bigger SQ differences.
Love how so many folks quote other sources as an authority without having any personal experience of their own. And then even put their own cred on the line by defending those sources.
“What do you think is the best at the moment? What are you using?”

@rixthetrick,

In my system, both AES/SPDIF and USB outputs sounds superb. I have decided long ago that I won’t rely on external ‘band-aid’ solutions to fix the inherent issues with devices like laptop or Mac-mini to stream music. My streamer and DAC has SOTA internal clocks 😊
I have FEMTO clocks on both ends, and I mostly use USB, and did use a carbon coaxial cable from my Cambridge Audio 4K Bluray player.
I found my fanless PC with linear power supply sounded better in my system.



rixthetrick
Imagine if it were possible to have a totally solder free set of cables, or crossovers, amplifier etc. Cold welded USB, XLR cables and speaker cables.

- Hot welded: Allnic Audio cables.
- Ultrasonic welded: Blue Jeans cables.


I am disappointed that digital hasn’t yet universally beaten the older methods of analogue recording and retrieval. With constant advancement, and new data transfer protocols, newer technologies in processing the digital format to analogue - I hope one day it will.

Most Hollywood movies now have digital VFX composited with live action. On a 40 ft theater screen, it’s almost impossible to tell the difference. Seamless.

The same sophisticated digital technology for audio is already here. (Behringer DEQ is using some form of it.) The full monty probably hasn’t trickled down to home audio because there’s no consumer demand. Most consumers are happy with MP3 on their ear buds. (But, there is a huge demand for superhero action movies = huge box office profits.)

DaVinci Resolve combines professional 8K editing, color correction, visual effects and audio post production all in one software.

Post removed 
"hey grandpa.. check the date on your flip phone, it is 2020"

Hey kid, check the battery on your newphone, it is at 6%.

By the way, when do you find time or enthusiasm to listen to a million songs?
@steakster - thanks for that, did a lot of reading. Learnt new things, brilliant - cheers
I noticed a significant upgrade in clarity going from Usb DACs in the 1-2k range to a dedicated streamer/dac with Ethernet in and I was using a well regarded usb reclocker etc. The other thing I did was add an Ethernet extender so there is no physical connection to the noisy router. Because of this I was able to use a very short run of high quality Ethernet cable to the streamer. Doing AB comparisons, there was no comparison. Ethernet cable direct to the modem had less clarity and more grit in the sound. 
I’ve played with different transmission types and they all have there pros and cons and work well. USB is fine from my experience. Like to OP I had a Innuos.... Zen and Zenith in my system. (Ended up keeping the Zenith) I’ve A/B’d many cables from Inakustic, Qudioquest, Acoustic BBQ, Ocelia, Cardas and they all worked without a hiccup in either and Aqua or Ayre DAC.

Might the OP have a faulty port at one end?
@ianderson 

the Zodiac Platinum USB port isue on Linux is fixable by inserting an USB Hub. The point of the thread is the variability of outcomes on the USB connection as a function of different cables, reclocking and galvanic insulation. The range of outcomes makes reviews of USB Dacs borderline meaningless. While one might get lucky with a high quality connection out of the box, nobody can know quite how good relative to various ways of tuning that connection actually is. Not great for an industry standard
There is a Audio Device Class for USB. 

The Audio Device Class Definition applies to all devices or functions embedded in composite devices that are used to manipulate audio, voice, and sound-related functionality. This includes both audio data (analog and digital) and the functionality that is used to directly control the audio environment, such as Volume and Tone Control. 

Don't fault the USB standard for manufacturers who fail to follow it or do so incompetently.
...........As well as tons of variability in implemented Ethernet connections or eth cables, i2s, spdif, tos...etc...  
Because a product and or more importantly, a specific use case has an issue, doesn't fault a connection type in the broad spectrum.  Far from it. 

With all that has been learned and the advancement in USB, if its well implemented, its probably going to be the better connection in said device.
Will Ethernet connection (or maybe better yet fiber sfp) be the standard?  Maybe and that would be great.  However, there aren't many GREAT Ethernet DAC's available though as compared to USB. 
to  rixthetrick:

I note and appreciate your expertise with respect to USB cables. I also noted that you used to make curious' cables. I am currently trying to find a better usb cable (than the one that came with the Chord Dave Dac). I appreciate good articulation, soundstage and correct timbre or tonal character of instruments (listen to classical and jazz). Would you please offer your opinion on which USB would best meet my criteria. The rest of my system consists of Rogue Audio's stereo 100 amp, RP-7 preamp, nordost valhalla cables and sonus faber amati tradition speakers.

Am I incorrect to assume that separating the power "lines" from the data "lines" is important?
Does the use or copper vs silver vs copper plated with silver make a tonal difference?
What do you "look for" in the cable construction to identify the quality and sound characteristic?

THANK YOU!!
craig
Post removed 
@craig,

If you’re still in the hunt for a USB cable, the I would ask you to consider buying Network Acoustics USB III cable. This is the best sounding USB cable (and I’ve tried many) that is meticulously crafted. Each of the Data, Ground and Power conductors are physically shielded, separated and isolated from each other. The cable is made from high purity UPOCC conductors yielding to exceptional realism and natural sound.

If you’re feeding signal from dedicated streamer or server to Dave, I would also recommend their ENO Ethernet filter. These two products has transformed my digital streaming experience.
Not just the Marketers!  I also am using and ENO USB cable and Ethernet filter.  They are sweet and highly recommended.  They absolutely made an immediate and unmistakable change.