The problem is Scott, the sub has to be connected to the receiver to create the ground loop. If you simply take it to another room and plug it in, there should be no hum since it is no longer connected to the receiver.
Agreed...if it is ground loop that is generated at the reciever. We don't know that it is ground loop or generated at the receiver yet. But in retrospect, I guess the noise does go away when the RCA cable is disconnected. So it stands to reason that the interference generating that noise is from the cable or device connected to the cable.....receiver. C'mon Wayne LOL, is that thing welded into the wall???
I am just trying to narrow the possibilities so we can move on to a solution. Suggestions?? I'm too curious at this point.
Good, cause we could argue over the better of welding/brazing/soldering the unit to your sheetrock...lol, or not.
Anyway, good news, the cable sheilding must have been either shorting into the cable or floating...either way, the old addage of checking what you did last creeps up again....anyway enjoy the LFE's without a hummer.....;-)
There's the value of troubleshooting for ya. A damaged cable. Most likely at one of the connectors. It sounded like a ground loop, which wouldn't appear until you connected the sub to the receiver, thus completing the circuit, but not in this case. These things can be a real bugger.