@charles if nothing has changed, (ie device you are hooking up to, the cabling, the outlets, ets) then I would be hard pressed to think it is a ground loop. However, you can connect it to a different outlet that is on another circuit breaker to check. If you have an extension cord, that is the easiest way to run this type of test.
Did any of your cables go over the Ice Power Amplifier? If so, move those beside the modules. They could be picking up noise from inside the case.