@Audiophile Neuroscience i agree with you, there is no black and white answer over which interface sounds better (coax vs usb), it comes down the effectiveness of the hardware implementation.
I guess if there was any message of enlightenment that I wanted to share with the world from my own journey, its that in the context of audiophilia, digital transmission does not equate to lossless transmission; despite faux beliefs thats bits are just bits and thats all there is to it.
ignorance and 1 dimensional thinking and pre-judgements around such issues do result in beneficial outcomes to the beholder; piece of mind, cost savings etc... ignorance is truly bliss.
I understand for some at various stages of their journey they may experiment and make a judgement call about the impact of certain cables or interfaces in their system and write them off as non-sensical using the bits are bits concept to dismiss such phenom; which is great - one less thing to worry about or cost to deal with right?... it helps us sleep at night... because at the end of the day, we all have limits to how far we're willing to take this journey right
For people going through their audio journey, depending of where they're at, it can be like putting F1 racing tyres on a Toyota Yaris. Do digital interface cables (Coax, USB, AES etc) impact sound quality? Do F1 racing tyres on a Yaris make a difference? Ask the Yaris owner and they'l say no. Ask an F1 driver if tyres make a difference... you'll get a different response. They both believe what they do based off (hopefully) their listening experiences; the actuality of the matter however is that ignorance does not equate to truth, only convenience...
For what its worth I'm not actually a huge believer in higerh sample rate file formats (96khz/192khz/DSD etc) - I believe they can improve the audio experience in low end systems simply because they reduce the maximum margin of error for timing errors/jitter during digital transmission; more regular digital samples, less deviation for timing error deviations between samples. I guess getting a higher sample rate file is also more cost effective than worrying about quality digital cables ; )
But yes, many do prefer a well implemented CD player. dCS' number one selling product is a CD player, not their amps, not their streamers, but a (albiet $55k) CD player... if all digital sounded the same, why does't my $55 Sony DVD player sound the same via Coax output than coax from the $55k cd player? bits are just bits.... (and yes, CDs do contain parity reconstruction data... so they're error corrected, data is perfect)
One often hears the argument that so long as the digital signal is galvanically isolated, buffered and reclocked at the DAC end all errors including timing are eliminated (so long as the buffer doesn't run dry. You are left with whatever intrinsic errors that may be introduced at the DAC end. John Swenson I believe with his work on PHY demonstrated noise on the signal entering the DAC receiver can induce noise originating inside the DAC causing jitter even at the outputs. I'd be interested on your take on this...and how it might relate to the OP question (if not then off to another thread)
thank you! love this,... I was alluding to this with my audiophile network cable comment earlier, but decided to let it go unless someone cared enough etc lol. So yes, any electrical noise entering the system (including emi/rf from USB or Ethernet cables) will ultimately result in additional jitter within the DAC... this is why quality, low noise power supplies can dramatically impact the reproduced analog signal...
As I mentioned earlier in a previous post, jitter is the death of audio quality in the digital domain... noise (electrical, emi, rfi etc) ultimately results in jitter.
Jitter and noise is introduced via USB cables due to quality/design of shielding, dielectric material (insulation), conductor material and cable design (eddy currents). (ethernet cables are no different unfortunately).
Your network switch also introduces a lot of electrical noise, transmitted down your network cable results in dac jitter...upgrade your $2 smps network power supply or change it to a quality alternative and you can be surprised....
Everything I've posted thus far has been via the intent to help the OP understand why their USB implementation sounds dull and lifeless.
If bits are just bits all digital sound the same (i guess that means.... like analogue right?). Digital audio is a lot harder to get right than analogue simply because there are so many misconceptions of what can't possibly impact audio quality... when one realises that everything affects everything they can move forward to a new level of engagement... albiet at what cost and sacrifice we have to make in this insane audiophile world to achieve such performance, is upto ourselves.
The cost of high performance digital interface cables (including usb cables) in light of theory that bits are bits can be offensive to the thinking/pre-judging types, but when one experiences the profound difference they can make in a quality audio setup, this is no substitute or looking back.
For the OP, their dull and lifeless digital audio USB experience is a result of poorly reconstructed analogue signal from jitter... no USB transmission theory will help them, but rather vectors and solutions to investigate and address them in their ultimate journey to audio satisfaction.