I had a ground loop hum not too long ago, found the source to be that our lawn guy had bumped the ground wire at the connection to the home ground rod ... a quick and determined reconnection of the wire to the ground rod rectified the ground loop.

I'd check all cable and outside home grounding sources.

Also, whenever I had grounding issues involving the cable coax the hum came through the 80s and not the 600....whether or not it makes any difference where the hum comes from, I don't know.

Rick
Our Room

smile