I have an RCA audio switch box that I’m trying to use to switch input from a TV and computer. The input from these two devices go to an amplifier that drives my two speakers. When I run either the TV or the computer through the switch box everything is fine. When I hook both devices to the switch box I get a hum through the speakers. I read about group loop hum on this forum but really not sure if that’s what I’m dealing with. Does anyone have any suggestions as to what may be going on?
The ground loop could be coming from either device, but the TV (if it is cable or satellite) is the most likely culprit. Those systems have a ground reference outside of the house so it will cause problems. I’m lucky in that my cable box has a TOSLINK digital out so it is completely isolated. I would search the site for help in diagnosing the source of the hum, PS audio used to have a lot of information on that in the past, but quite honestly I have no idea where it is or if it is even still there. Good luck!