Reference the hum, although in my case it is more of a "buzz" then a "hum," mine is associated with my cable TV coax cable. As soon as I disconnected it from the cable box it was gone. Touch it back to the box and the buzz comes back. I originally thought disconnecting all of the inputs from the cable would do it if it was being caused by the cable but I guess it has to do with what the cable is introducing to the A.C. current. But I'm no expert. All I know is that the noise is completely gone once I disconnect the cable. They obviously anticipate this problem because it is one of the fixes listed in the manual.

Regards.