I heard the Yamaha M5000 with the top end Yamaha preamp and the great NS5000 speakers in the dumbest dealer demo room possible. I tried to ignore the room, but it was hard. However, I did think the speakers were likely great because i enjoyed them in that glass walled "boardroom". They were giving me some problems, but I tried to listen near-field to mitigate the reflections. I liked the amp and preamp.
At that time, I had my heart set on buying the Luxman m900u because I thought it was more engaging but that is not a far comment given the stupidity of that demo room. I had heard the Luxman m900u at a different dealer in a better room. If I had the cash at that time, I would have bought the Luxman on the spot. It seemed a little bass shy but that was not a concern for my small room. The Yamaha seemed to be stronger on the bass, but the room again was likely doing that.
I bought a new "warm" amp last month and I was considering the Luxman and the Yamaha. However, I went with a KRELL Duo 175XD instead. I own the KRELL K-300i integrated and I really enjoy it. It is not as warm as the Luxman nor as neutral as the Yamaha.
The other amp that I have on the horizon is to upgrade my CODA #8 to the CODA #16. That is a killer amp and one I was thinking of upgrading on the spot in November 2021, but I started thinking of my wallet. That one sounded somewhat like the Luxman. maybe clearer sounding. The CODA #16 I will get will be $13.5K (or $8K upgrade)