What is the best solid state amplifier you have ever heard?


What is the best solid state amplifier you have ever heard?
jozurr
The three that are all in systems that are used regularly with widly various components/cables/interconnects/ pre(but all tube pre)/sources/speaker combos are:
Bedini 100/100 in system at my office
Levinson 23.5, aecond system
Pass 260.8 mono's, main system

No thoughts to any future upgrades 
yyzsantabarbara

I have not heard the m-900u. As good as the 509x is I am sure I will instantly want it...but from what I have heard, it really needs to be driven from the c-900u preamp to totally manifest its magic. This is not in my budget at this time. That being said I could step up to the m-900u and use my dac as pre for a while...but not sure if I’d actually be in a degraded state from the level I have now...which is the best system I’ve ever assembled in this often torturous journey. I recently came from pass x250.8 and xp20 combo. Excellent gear no doubt, but there is more realism and soul, to me, with the 509. I remain sort of in a state of disbelief as the weeks roll on. Thusly I think I’m better off pipe dreaming about the 900 level stuff but in the meantime totally enjoying this wonderful integrated.
@stevea11757 
Are the  Pass 260.8 monos really good - i.e., tone, body, drive?  They are sort of on my short list of amps to consider but would be a downward move in power for me.  Are they warm, lean, neutral?  How about resolution?  Do they have a lot of drive for inefficient speakers....not crazy hard to drive but like 86dB efficiency, a minimum impedance of 3 ohms, and a fairly innocuous phase angle?  I would appreciate any feedback you care to share.
Spectral is a line I wanted to be impressed with, like Pass, and I just haven't. They do not bring me joy.