Yamaha AS-XXXX....a dream that never came true. But I can tell you the story of Yamaha R-N803D vs Technics SU-G700M2.
In 2019 I upgraded from Yamaha R-N602 but the difference was marginal, i noted some subtle bass better response for my Monitor Audio Gold 100 G4.
This year I found a disdained SU-G700M2 unit, his owner was disappointed with the brightness of his B&W 802 D3 ( 25k euro pair) with this amp and I got the amp.
R-N803D is a consumer receiver and for sure AS series is far better, unfortunately I never had one, but the difference between SU-G700M2 and the former is pronounced and notable.
When I first plugged the SU-G700M2 I was immediately able to feel differences in bass response, dynamics and clarity but the moment I returned to R-N803D I heard all that is missing. Don't get me wrong, I had wonderful moments with Yamaha but .... "Grand Master Class" is another class. It was like a veil was removed from the music and everything was better defined.
900 euro vs 2500... Is this worth it? ... Long term yes :)