@Duine
That's one of the reasons to get even a USB DAC and amp, so the analog parts are isolated from the insides of your case.
@hj

@matrix @Duine you might still get noise since you're connecting to USB electrically, you're not isolating anything, and have to just trust that your USB DAC has proper isolation and stuff, that's probably why hifi equipment tend to have "ground lift" switch to actually isolate ground wire (i.e. for USB it's the metal box of the plug IIRC). If you really need electrical insulation period - use optical instead, but for me at least my Roland Rubix24 works great over USB, but it is somewhat hi-fi.

@hj
Oh yeah definitely, but that's going into autistic audiophile territory. USB is enough in majority of cases.
@Duine