I'm here to leave my 2 cents regarding USB cables.
The only place in my entire Audio devices where I use a USB cable is with my headphones - Focal Bathys (in USB DAC mode). I wanted to replace the stock cable as soon as I got the headphones - not because it sounded bad or anything, but because of the lousy quality. I ended up buying 2 cables - a "generic" braided cable that aesthetically fit with the headphones (UNIQ brand, 1.2m), and I wanted to try out something more hifi, even though I had 0 trust digital would make a difference - I found a Audioquest Forest (1.2m) cable for 50 euros - so I bought it.
For the fist week of using it I was working heavily and although I had some spare time here and there, I didn't have a proper time to fully listen and switch cables to tell if there is a difference. To my ears, with those limited tests, they sounded absolutely identical.
However, today, I spent all morning really listening to any differences and taking notes. And to my COMPLETE surprise, I'm genuinely astounded.
Yes, I am a skeptic when it comes to digital audio cables. Yes, I understand that what we can measure doesn't really show EVERYTHING when it comes to audio and it's very complicated.
But I can absolutely now guarantee that there is a difference. Notably, listening to Michael Jackson - Liberian Girl, Steely Dan - Aja and Tool - Fear Inoculum, what I can say in short is that 3 things are very obvious:
1) Instruments like the snare and other sounds with high frequency that sparkle have a MUCH more natural and longer decay and they simply sparkle more, are more obvious, there's more "air" up there
2) The vocals, especially Michael Jackson's, has more weight and is more present
3) On Fear Inoculum it's quite obvious that the soundstage is wider - I can literally feel some instruments from coming from further back behind my ear canal, while on a generic USB cable it comes in front of my ear canal. Think of it like this: With the generic cable, the literal stage of all the music and instruments is let's say 90 degrees in front of me, arranged on a semi-circle, while with the Audioquest it has at least 10 more degrees of horizontal 3 dimensionality on both left and right. IT's more... 3d i guess? Holographic some people use? It's more complete, more encompassing, in plain English.
No, I don't know why it is. Spec-wise, the Forest has 3 things standing for it: A well isolated live wire for the charging, semi solid conductors (vs braided on generic ones), and they are also 0.5% silver. Do with this info as you wish, but overall, there is a difference, and it's very positive. Now I'm curious how the AQ Carbon sounds.
Yes, I have listened for half a day, it's very fresh in my memory as I'm writing, the difference is real, it's there. I never bought high end USB cables in my life before or used them.
My stereo system is completely connected via Van den Hul cables (speaker and intercoonects) and I have a Coax digital Van den Hul cable connecting my CD transport to the DAC. My power cables are all Supra. I have no idea how good they are or if they sound better than cheaper cables. I got them as a package after negotiating for my stereo setup for a very good price, so these were my 1st and only cables I ever used out of the box. And no, I'm definitely not affiliated with AQ - this is the only AQ cable I've ever had.