noise ..noise..noise..

Sounds like power outlet,tubes or transformer noise by your description.Then again you might be hearing the difference in the preamp section's gain output relative to the amplifier's input sensitivity of the integrate.

In layman terms it's like having a preamp with too much gain for the amplifier.You get that background hiss in the music.With the volume turned all the way down it is very noticeable.

Maybe the amps just have a little too much noise for your very efficient speaker system.
With speakers like that, you need a very quiet amplifier.
With most other speakers, the noise might be buried and you wouldn't hear it.

try turning your amp power down slightly to compensate for the higher input power and if that doesn't work try disconnecting your cable for your tv because if your ground in your home is bad your system will ground itself through the cable. I had this same issue and both of these solutions worked well for me
I hope they help you Greg