My thought is the amp is straining, hence the thread. The receiver is running an outboard MX2 amp, 125wpc (although somewhere I read it was 150). Perhaps there's a gain issue between the avr and amp, but as both are Yamaha, I didn't really consider that. All I can say is that movies/tv are usually around -15 to -20db on the volume display. When I'm really cranking it, 2 channel, home alone, etc, I'll crank it up to 0db or possibly higher. the 'max' is +16.5. Does that mean anything to anyone in absolute terms? I understood it better when volume controls were a simple 1-10...
Anyway, since the problem is only a problem for me at 'I have the house to myself, time to let the neighbors know I'm home' volumes, I'm reasonably sure it's the amp running out of power.