Originally Posted by basshead81
beeman, its plugged into the wall via a usb cellphone charger.
IIRC, you mentioned two situations. One where the miniDSP was plugged into the USB port and one where the DSP was plugged into the wall outlet, hence why one situation has a ground loop issue and the other doesn't.
Which raises the question: does the miniDSP have flash memory that allows for holding programming information?
Commenting on that which I'm sure you're aware of, anytime, anything is connected to house wiring, if not using the same "outlet," to various degrees, a ground loop can develop. This applies, even if using the same circuit breaker but a different, same-said, down-the-line outlet.
FYI.....if two audio appliances, are on the same equipment rack, and electrically, they're connected, a ground-loop condition can appear. It really is that esoteric.