USB is quite different than Ethernet. Isochronus mode USB has no error correction ability, and there's the Vbus/Ground lines that can negatively impact USB DACs. Some people have reported improvements simply by putting a piece of tape over the power leg pins on the USB connector. Ethernet doesn't send any power, and it's error correcting. Beyond using a shielded cable, I'm really struggling to understand why spending a lot of money on an Ethernet cable makes any sense.
WHY YOU ALWAYS GOT TO BE CORRECTING ME!!!
Nah just joking thanks for the info, changstar wouldn't be the same without you dave