After a day or so of tinkering, I found out my plasma was causing the noise, potentially with the DC voltage in the line issue that isn't uncommon.

Only device I found to combat this was the Emotiva CMX-2. Got it in today and fixed it perfectly. Anyone that runs into the issue and thinks it is a DC issue, give this thing a try.

Hum
https://www.dropbox.com/s/shevqhnhz049zom/Hum.m4a?dl=0

No Hum
https://www.dropbox.com/s/bgvzb0v69uig4pg/No%20Hum.m4a?dl=0

I have a 7500 too. I am getting ready to send it back for repair under warranty. It has a static sound in one channel (right surround) that does not vary with volume, and is heard when muted too. I did all kinds of input cable swapping and speaking wire swapping to isolate the problem. It is the amp. I have a plasma too, but I don't hear transformer noise in any of the channels. I do use ferrites on the power cord to the amp and TV.