I have read this site's article on ground loops, but am having some trouble understanding my situation.
First of all, my house is old and has original wiring from the late 20s, which incidentally does not have ground wires. None of my previous AV equipment is grounded save my subwoofer (unfortunately have to use a cheater plug). My AVR is connected to my television, and I have never had ground loop problems in the past. All my AV equipment utilizes one outlet, except the subwoofer, which utilizes a different outlet, though it may share the same circuit as the rest of the AV equipment.
After adding the SMS-1 to the picture, my system developed a light "hum", and although the transformer that is between the SMS-1 and the outlet has a ground prong, the wire supplying power to the SMS-1 has only two conducters. As well, the SMS is plugged into an ungrounded outlet. Removing any connections to the subwoofer would not alleviate the ground loop. In swapping cables, only removing the sub-in cable that is coming from the AVR will alleviate the hum. The cable itself is a 75 ohm coaxial cable originally sold as a composite video cable.
Does a solution seem apparent without using one of those ground loop cheater thingys, and how is it that I have a ground loop in an ungrounded system? Any help would be greatly appreciated.
Thanks,
George