Yes, I should have remembered that. On the whole Yamaha gear has low output from there preouts with zero head room.
This is definitely the electronics as his integrated amp solves the issue. The answer lies in these type of issues and whether he really is using his preamps section straight with no Eq.
Even with my Marantz units, I have to lock them down tight to stop Audyssey functions bubbling up and causing mayhem.
There really is a need for receivers and pre pros that really are essentially just wire with gain, and not mucking about with the frequency spectrum.
I can tell you one thing, if there were more higher caliber speakers around, people would be abandoning all this auto Eq nonsense in drives. There is just far to much unwanted, not needed, quality spoiling complexity in current AV gear. Simplify, simplify should be the mantra and we would all be better off.