One more thing to report.

The hum coming from the amp (this is not being imparted to the speakers but is humming noise coming from the amp itself) is a bit louder than the B&K and is always there, even when the system has warmed up a bit.

How loud is it? You can hear the hum even with the XBox 360 on (with no disk spinning).

Is it noticeable when the system is playing music or a movie? Not really, but it is there nonetheless.

Anyone else have a 7500 or 7700 that makes a noticeable humming noise?