Different receiver with better sound quality amp?
I can only relate it the car stereo amps I have done. I swapped some OLD Kenwoods for newer, more efficient, more power Alpine ones. The HISS, noise floor was immediate. I hated them. Sold them and went back to the old Kenwoods. Son's car we got a lower model JL Audio amp, same thing. It lost a channel and we put the old Kenwoods in (they were in my Sonata). He said the same thing, much better for the transitions etc.
My daughters CRV I bought an AudioControl amp mainly based on that spec of low noise. It's VERY nice and quite with plenty of power for her.
I recall the Dolby and THX certifications from way back as part of those things for the home audio.