Sounds like faint RFI from the cable line. Only way around it would be to have a way to disconnect the cable from that room if you're not using it or have each cable run be a "home run" to each room from a central panel. The latter is how mine was run when I built the house. Then how often are you going to have the volume on the audio system up to 100% with no signal. Maybe Ivan knows of some simple way to eliminate it. The hum from the Mc amp is a bigger issue I would think.
__________________
Jack
|