ProtegeManiac
Headphoneus Supremus
I just don't know why I didn't get this background noise at all with my old PC and the E10. Ever since I got my new PC, the noise coming through the USB ports is awful, or at least it is with the E10. My FiiO X3 doesn't have any audible background noise when using USB.
It depends on the motherboard and the PSU. Sometimes it's low power output, sometimes there are interactions with a lot of stuff in there, which is why potentially there are a lot of problems with using a computer. That's why some motherboards now are advertised as having 5v on all USB ports (even simultaneously) as well as some kind of shielding on the audio circuit (like ROGs that have them on daughterboards or Gigabyte isolating the analogue section on the reverse side of the PCB).