In theory, if a source is not sending a signal to the amps for amplification of that signal, then there should be no electrons traveling through the speaker wires to the speakers. But I did notice that with my HK 7200, I would hear a very slight hiss/hum under these conditions, and the 7200 was HK’s flag ship AVR a year ago. With the Rotels, I hear nothing. This lends itself to a thought that possibly, the amps in a receiver are still sending a ‘stray’ signal to the speakers, while separates do not. I’m still in the learning stages of how all these critters actually work, so I’m just speculating here. Maybe others with knowledge of the intimate workings of audio electronics can provide insight.
Or, you could be picking up stray noise from other AC wiring in close proximity of your speaker cables. Again, just guessing.
I too enjoy the M80’s more every time I listen to them. I’m in love with them now. They were great before with the HK, but they’re fantastic now with the Rotels.