This sound is like data moving through a bus, or hard disk activity, etc. I am sitting here in the quiet, except for the occasional faint screech of computer noise coming through my speakers. I have only heard this before when using the audio out built into a laptop, never on a desktop computer. I might have to try another motherboard, but that would suck.
The computer is normally grounded, UR 44 is not via the factory power supply, and the audio AVR is normally grounded. The Focusrite that did the same was USB powered.
This doesn’t seem like a grounding issue due to the intermittent nature, but I suppose there might be something that would make a difference. Can’t imagine what.