Just to throw out...if any have problems in the future. Several 'hum' type threads I have roamed recently where weeks were spent trying to isolate the culprit turned out to be the coaxial cable 'ground' (to the ground).

I've watched at least 4 people through very long Convoluted threads asking for troubleshooting help (and trying just about every know method of isolating the hum)finally track various noise in a system to this source...they had spent a lot of time isolating due to 'clues' which sent them looking at various components when hum exhibited only on 1 or two inputs when selected but not active. In these instances 3 had problems due to the fact that the cable had been grounded to a second location rather than the 'main' location the rest of the house was grounded at (2nd pole in ground).
One just needed to retighten screws which snugged the ground wire to the grounding stake.
As Jeff stated: "And your system includes just about everything connected to your home's electrical system - from the breaker panel on in."
This can be a hairpuller when these issues arise.