Why do digital coax cables matter?

From what I've read:
Digital signals travel through the cable at very high frequencies, they are different from the signals that run through interconnects. High-frequency signals travel to the outside edges of a conductor, the "skin effect," and silver is a better conductor than copper, hence you have silver-clad cables.
I had a shoot out between USB cables in my system, Pangea PC (silver clad) vs Audioquest Forest (copper), and the Pangea wiped the floor with the Audioquest. No contest. The Forest sounded dynamically compressed, like the speakers were covered with a wet blanket. I am assuming the same would be true of digital coax, but don't know from experience.
The length of the cable matters as well, shorter is better for USB, longer is better for digital coax. The coax issue has to do with reflections within the cable that create timing errors in the signal, 1.5m minimum is what you want.
The connectors matter because their impedance can be different than that of the cable itself. All digital coax cable is 75 ohm impedance. It is difficult to create a true 75 ohm RCA connection, BNC connections are easier to create as 75 ohm. Very few DACs or CD players have BNC connections tho.

They sound different to me. I've tried several budget brands and I have found them to sound noticably different. Logically, they should not sound different since it's sending discreet values, not an analogue electrical stream, but they do sound different. The only explanation I can think of is that the clock signal is sent on the cable and therefore there can be jitter introduced by different cables.

Two things that I have learned through experience with many digital cables over the years.
1. Digital cables can and do sound different from each other. Or put another way, some sound better some worse.
2. A $200 cable may or may not sound better than a $100 cable. I have owned digital cables that retailed from $86 to $3600. I'm currently using a $200 digital cable that I'm very happy with.

Think of the range of answers to your question as a knob on your amplifier. You can turn it from hard left (7 o'clock) to hard right (5 o'clock). Or you can stop at any point in between.

Say hard left is the "complete skeptic" setting. If you put your knob in this position, you'll think that all USB cables sound alike and that anyone who hears a difference is a fool deluding themselves.

Hard right is the "magic" position. There will be vast and obvious differences between cables for reasons that probably involve Star Trek warp drive principles.

Move the knob to the middle left and you might think that, under some circumstances with certain equipment, RFI noise can subtly affect results. Move it mid-right and the difference between cables is heard more often and with greater clarity, and the technical explanations will go up a notch in creativity.

So, dial in whatever setting makes you happy. Just remember that no matter which one you choose, there will be plenty of people ready and willing to tell you you're wrong.

I know a guy that makes and designs cables. There are some reasons known why cables in general sound different but exact reasons are not always well understood - he conjectures it has quite a bit to do with the dielectric. But sound different they do as you will find if you listen to them. If you are afraid of being fooled do a simple blind test.

Thanks
Bill

Because $500 one must sound better than one for $20 under First Amendment of Audiophile Bill of Rights.