Have you given the Blue Jeans Belden 1505a a shot. It may not have audiophile cred but It is rated out to 4.3 GHz and measures very well. IMO digital is very different logic to analog cables, your DAC only cares how well the cable transmits a square wave which can be easily measured. I much prefer my 1505a to my Furutech silver coax cable, so thats one to avoid. In coax cable silver just reduces resistance.
For USB I am using a silver cable from PPAStudio, some of the construction is a bit iffy but it sounds best out of the ones I have tried. Once again better than my Furutech GT2, and Oyaide UPOCC copper USB cable. I'm not sure if it performs better than the fabled monoprice USB
. Some of the high end cables seem to have conflicting impressions, maybe they have trouble terminating them consistently or something because of crazy geometry etc. I have also tried Wireworld ultraviolet which compared to my PPA was more lively in the treble and warmer in the bass. Next I think I will try the new USB cable from PPA. I seem to like the flat cables that try to keep consistent geometry between the digital wires.