Yes, everything was on the same circuit. The raised noise floor was not ground loop hum. I'm sure those who have experienced ground loop hum know the difference in sound. The higher noise floor was still there when everything else was off and disconnected.

Unless it just happened to be something odd that one day. Because in previous testing, I thought removing all the inputs but leaving everything there did lower the noise floor quite a bit. Not as silent as it is today though. Based on what I can hear with my ear against the grille.

I did try physically moving the EQ, but only a little bit, thinking maybe it touching the DVD player or not touching the amp would make a difference. Turning off the EQ would stop it from generating any EM fields.