Alan, you're the Man! Unplugging all the cable tv connections and power didn't solve the issue, but plugging the sub into the same surge protector as the tv and other a/v components did. The sub was originally on the same circuit but a different outlet and surge protector. So the question now, given the sub's power cord length, is whether there is a method of isolating this voltage differential so that I can again move the sub further away if better frequency response dictates. I'm not familiar with the isolation transformer electronics - is there a type that can be put in the path of either the coax or balanced cable that might do the trick?
