I’m not use to hearing surround sounds at low volumes. So many sounds in the movies I didn’t hear before are now audible. I’ll have some time this weekend to re-run audyssey and make a few manual adjustments. Music doesn’t get fatiguing at higher volume. Everything is extremely clean sounding. The muddy sounds at -10 are gone and music is satisfying at -20 even across the room. I lost some of the soundstage and imaging but I think that’s due to the avr being uncalibrated. I am assuming the level adjustments will come down due to the extra power.
It makes sense that music is not fatiguing at higher volumes. The only way that music can be more satisfying at -20 though is if your Denon's amp gain is lower than the ADA's. In my case, the Onk and ADA gains are equal. I heard no difference at lower volumes even in 5.1. If you're running 9.1 then maybe your Denon is finding it difficult to cope with peaks even at lower levels. Or maybe your Denon's power supply is crap compared to my Onk.
There should be no difference in soundstage and imaging in stereo at lower volumes.