USB Cable

@tvrgeek interesting discussion of how the USB interface could become noisy and why.  Seems from your discussion that you lay more blame for any differences in performance on deficiencies in equipment design rather than the cables.  I am wondering if you've done any listening tests yourself to see if you hear a difference in different USB cables in application with different gear and in different settings/electrical environments?  Have you, for example, done listening tests comparing a "premium" USB cable with an off the shelf Belden and/or generic Chinese USB cable in different settings?  If so, what did you learn?

It seems to me that you focused most of your discussion on the relationship between digital cables and the immediate gear they connect.  But things can get very complicated in actual user set ups, often with multiple pieces of gear and their cabling creating multiple electrical fields in the neighborhood of your computer/streamer and DAC, not to mention all the other electronic devices operating in your vicinity.  This along with variables like the different physical proximity of devices to one another and differing levels of power conditioning and noise suppression in different set-ups would seem to make empirical testing of different cables in different applications a must.

Your mileage in terms of performance and what helps or degrades performance of digital front ends in the context of cabling may in fact really vary, and it may be in part dependent on factors that are beyond the relationship or designs of the sending and receiving devices in a single USB connection.

kn

It is the complex environment of what you speak. This is why USB and Ethernet cables are twisted pairs and shielded.  The designers knew this. Partly for the spec of 11 feet. USB was not intended to exist in a vacuum. 

Yes, I blame shortcomings on the end points not implementing good practice.  In a $100 DAC, it is cost driven so some slack is given. But in a $500? Nope. $5,000?  Pure incompetence. 

I did loopback tests between free cables and correctly designed USB cables.  Big difference and it shows up in a spectrum analyzer. Added an isolator, and presto, no problem.  Two piles, good and bad. You can add a braided sheath and a fancy box, but it won't transfer bits any better. 

Remember, it is not the digital waveform that matters. It is how it is detected, PE, NRZ,  windowed, etc and then gated into a shift register to be accessed by the DSP section. Even DSD is re-generated.  No place for magical properties to hide. 

FWIW, I just ordered a D400es and it does NOT have a galvanic isolator.  Bad design for that price point considering how much they spent on the cabinet. I will test  both with an analyzer and my ears if ones needed in my cabinet.  I pay attention to cable dress  and common power so It probably is not. I have dead silence through my speakers with no active signal. 

Thanks for the reply @tvrgeek. In addition to testing with a spectrum analyzer, have you done blind listening tests to different digital cables? 

Between good cables, no I heard no difference. I am not positive I heard a difference with the bad cables. Knowing they are bad etc.  I had my Grado's then which were more revealing than my Yamahas.  If it measures bad and measures good is cheap, why not? 

There is actually no such thing as a true blind test because you know it is a test. Your brain will make up answers.   So, we get larger groups trying to take guess averages out, double blind and all that. Guess what?  When there is no difference, we get answers that are positive they heard a difference, and when a difference, sometimes large, some claim there is none.  Do enough trials to where statics start to matter and fatigue sets in and your brain makes up even more stories.  Some studies may be as close as 60% and claim that is proof.  If you know stats, you know far that is off!  That is the problem with subjective tests. They are only valid for you and may or may not reflect reality.  Your perception is all that matters though. Being human. 

When we make a change, we usually jump in and do "critical listening"  and hear details we had not before. Were they really revealed, or were you just listening to music before and not noticed them?   I know I have fallen for this.  The more your invested in the change, the more likely you can switch back and those details get blocked.   Sometimes we put something and because it first seems different, maybe yes, maybe no, but a week later we claim it is "burned in" . More likely, we have just reprogramed our expectations and there was no change.   Speakers, yea I buy that.    We are a funny species. 

Question. @tvrgeek what is in your audio chain, equipment wise? DAC, Streamer, Amplification, Speakers or are you using Headphone. Just curious.