I am a Yamaha fan.
I never liked any Room Correction EQ - Audyssey, YPAO, ARC, Dirac, etc. You might feel the same.
When you switched to Yamaha and didn't use any room EQ, you probably preferred the sound without any room EQ.
Thus, I don't think it was a case of Denon SQ vs Yamaha SQ. I think it was a case of EQ (Audyssey) vs No EQ (Yamaha).
I think if you had turned off Audyssey in the Denon, it would sound the same as Yamaha.
But I am a fan of Yamaha.