Wow....that was easy. Nice call whoaru99....the cheater plug fixed it. Care to explain the ground loop issue at work here?
Grounds, at least in theory, will always be at the same electrical potential. However, when there are different grounding points or loose connections, there can be an electrical potential difference between them. If so, this can cause a current in the interconnect between the gear which often results in hum and, apparently in some cases, can cause protection circuits to be activated.
120V is dangerous so one must use due caution when working with it. Personally, I'd start by pulling the receptacles (after turning off the appropriate circuit breaker/fuse) that your audio gear (including subs) connect to and check the wiring. Ensure the (usually bare wire or green) ground connections are tight, that the white wires go to the silver screw/long slot and are tight, and the black wires go to the brass screw/short slot and are tight.
Might also want to check the receptacles with one of those $5 plug-in testers to see that it indicates proper wiring.
If neither of those two reveal anything unusual, then it's probably into the power panel to ensure the connections are clean and tight at those points, and that the electrical system is properly bonded to the earthing system. It would also be wise to ensure the main neutral connector is tight at the main lugs in the electrical panel board. Note that in many electrical panels the main lugs are always "hot" with no convenient way to shut them off.
And again, I must remind, you can be hurt or killed by 120/240V. Don't do this stuff unless you know the proper safety measures and are comfortable doing it. If you don't feel comfortable doing this stuff then call in an electrician. Probably will cost a few bucks but lots cheaper than a funeral.
