“Step #1: ditch using a general purpose computer as a streamer
Step #2: experiment with USB cables. Slowly ”
+1, @thyname
If you are not in a position to take step #1, then use a USB isolator to eliminate noise from your PC. You can use a generic USB cable between PC and USB Isolator and a high quality USB cable between Isolator and DAC.
Check out ZavfinoUSA, DH Labs or Supra for USB cables.