USB Cable

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. 

@tvrgeek Said "Between good cables, no I heard no difference. I am not positive I heard a difference with the bad cables."  Thanks for answering the question. 

I have heard big differences and no differences between cables in different applications.  I noted above in this thread that my favorite USB cable is currently made by DH Labs, but I have also done sound testing with cheap cables (all under $12) connecting a hard drive to a server, and I had a very specific favorite (my favorite was actually a "Belkin" not a "Belden").  That is when I first realized digital cables matter.  I assemble a lot of my own power cables, and completed cables I thought would sound killer based on design, materials and measurements just sound weird, and some cheap power cables from China sound fantastic to me.  Go figure.

On other digital cables - specifically coax cables - a vendor handed me some cables from brands I had no experience with to try, and then I went out and borrowed a bunch more from another vendor and I did a set of subjective sound tests.  Turns out I had particular dislikes, likes and likes more.  I had my son who has good ears for recorded music come sit down and listen to different cables and take notes as I swapped them out calling them 1, 2, 3 etc. He could not see what I was doing.  A blind test.  No particular order by price.  His notes generally echoed my non-blind impressions.  He hands down liked the two most expensive cables the best without knowing what they were.  He also really liked a cable that was the 2nd cheapest cable tested.  He did not like the cable I had been using and I thought previously was all that.  Turns out after going through the testing period, I didn't care for that much either when compared to other wires in the test.  Maybe he was tired, or confused, or the result was a fluke, or maybe he just has really good ears and could detect differences in sound attributable to nothing more than some wires and shielding and connectors running between a server and a DAC.  I bought an expensive cable as a result of this experience.  Maybe my gear sucks and needs that extra help.  Dunno.  But it makes me happy when I listen.  YMMV.

kn