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

What is the best solid state amplifier you have ever heard?
How do you isolate the amplifier? It's a system and every component, including the room impacts the sound. 
To the OP

(1) ricred1 nailed it ....full stop

(2) there is no “best” in isolation because of (1) 

(3 Without prejudice to (1) and (2)  above you already have three current posts and all with the same core theme



Bedini 25/25! I still have mine. Bought in 1980 from Innovative Audio in Brooklyn Heights, NY. Cost - $750. Used it with Quad 57's. A forgotten classic!
@roberjerman, I used that same combination myself for years, but sold my 25/25 about a year ago. Another worthy contender is a pair of BEL (Brown Electronic Labs) 1001 Mk. V's, ay? The only solid state amp Brooks Berdan liked and sold (he was enough of an idealist to insist on the former before agreeing to do the latter).
@akg_ca , well spotted.

It could just be a tautological posting error or perhaps something more sneaky...

@bdp24 : Speak of the Devil! I am sitting here looking at my BEL 1001 Mk I. Serial number 0001. The FIRST production one from Richard Brown! Sold to a friend of his! And subsequently purchased by me! That's what I call rarity! I don't at present have it hooked up. Awaiting some space at my abode for a pair of my Quads to be set up.
I always wanted a Brown Electronics Lab amp after reading that review in TAS so long ago! It was quite pricey at that time! A few years ago I found one on EBay and had the winning bid ($525!). I learned it was being sold by the original owner, a friend of Richard Brown (who passed away way too soon!). I figure it will be at least as good as my Bedini (now in need of repair) for use with my Quads and Rogers LS3/5A's.
Audia flight Stremento #4 mk2 very musical with great stage depth,imaging bass detail and great midrange and highs.Its very well built at over 205 pounds and looks great as well. 

my favorite solid state amp is the darTZeel NHB-458 mono blocks, followed by the darTZeel NHB-108 stereo amplifier.

I'm a guy who loves tube amplifiers. and the darTZeel does have a touch of the breath of life of tube amps, combined with a very, very low noise floor and extended and uniquely natural and smooth top end and wonderful micro-dynamic energy.

the darTZeel amps use a minimalist parts count in the signal path and are swiss built like a tank. amazing jewel like quality.

I owned the dart 108's from 2005-2012, I've now owned the dart 458 mono's since 2012.

With respect @akg_ca, I do not understand your concern with this thread. While I understand and agree with @ricred1 that "every component, including the room impacts the sound" the OP asked a simple question for respondents to post their subjective opinion of the SS amplifier they enjoyed hearing the most, i.e., the "best solid state amplifier you have ever heard." The answer to the question is certainly open to variations WRT listener preferences, room size/conditions, accompanying gear, speakers, and more, but there were no caveats as to system goals, power rating, monoblocks or stereo, room conditions, or whether the amplifier had to be owned, borrowed, in the poster’s system, in a friend’s system, or at an audio show or showroom.

For purposes of an internet thread, it is a simple question and I am baffled why people don’t either answer the question, or ignore the thread, but rather feel the need to take it upon themselves to "police" the OP as to the worthiness of their post. He/she may simply be looking at purchase options and trying to learn something. Sheesh, it’s no wonder some people choose not to participate here.
Nelson Pass kit - based on SITs, which have linearity and soft clipping similar to triodes. Makes about 25 watts.
D’Agostino, Luxman, Ayre are my top favorites right now.

I find their sound in sharp contrast with Pass, which is really not for me.
I once heard a Technical Brain amp at a show. It was the only time I liked a SS amp more than any of the tube amps next door. 

I don't remember if it was the integrated (it probably was) or separates.
Forgot, it doesn't get enough mention, but I also really like Arcam
It is hard for say what are the best amps I've heard, given the variability of setups, rooms, other components, etc., but, I can say I've hear some nice sounds from systems that used certain amps.  I've consistently heard nice sound from systems with Ayre electronics, so I suspect their amps are decent.  I've heard two First Watt amps, one in my own system (J-2) and another in my friend's system (SIT).  The SIT amp was actually his own build, based on schematics provided by First Watt.  I've heard a couple of decent sounding systems with D'Agostino amps, so they are probably top contenders as far as my particular preferences go.   I recently heard a couple different amps from the current lineup from Luxman, and they sounded good; I was particularly impressed with a low-powered integrated that seems to be quite nice for the money.

I've heard systems with top contenders, like Soulution and Constellation; the systems did not do anything for me, but, I cannot separate out the contribution of the amps, so I have no opinion about their sound.

A friend who is, like me, very much into the sound of lower-powered tube amps, said that he liked the sound from a system powered by Bridge Audio Labs (BALabo); that company is out of business and the amp was a six figure item. 
OK, I put my flack jacket on....

McIntosh MC452 (paired with a McIntosh C2500 tube preamp)
As already mentioned, an insurmountable degree of variables to answer properly. For entertainment value and in no particular order: Mark Levinson 29, Audio Research 100.2 and Pass Labs Aleph 30. Yes, I have owned all three over time and am currently using the Aleph 30. Have I listened to every amp on the planet, of course not. Are there better amplifiers, of course.
Ayre MX-R Twenty
My other favorite amps are either tubed or hybrid (ARC, Aesthetix)
Plinius SA-102 with a McCormack dna-1 gold revision a close second.

N.E.W. DCA-33 battery powered, 33 watts per.Real nice sounding solid state amp!I keep one around as backup for my tube amps, sounds great with my Sonist Concerto 4's!

Spectral Audio amplifier :)
At very first listen it revealed the coloured sound from other top contenders of 200 watts and up. I was amazed at the completely different level of overall refinement and level power output. 

Thank your for all the ones responding. For the ones criticizing the thread, if you don't like the thread, ignore and move on to the next. Your time will be best spent looking at more sensible and valuable threads than this one.

I'm learning more and more about amps. 

Thank you. 

@erik_squires yes Arcam stuff has been good for as long as I can remember. Always marginalising more towards warmth than most others.

With first rate reliability and support too.
In a retail setting; BEL (Brown Electronics Labs) MK-V's.
@ptss what spectral amp did you hear?
The two best I have heard in no particular order are:
Nagra Classic
Linnenberg Liszt 

For me, it was the Pass Labs XA-25; this is the one that made me finally move away from my 300b SET monoblocks!
Naim Statement NAP S1 monoblock amps + Naim Statement NAC S1 linestage preamp driving the Focal Utopia Grande or the Magico M6 speakers. 
D'Agostino Relentless & Momentum M400 monoblock amps driving some big Wilson Alexx or Wham.
Audio Research Reference 750 SE vacuum tube monoblock amps (2 pairs) driving (big-amped) Sonus Faber Aida ll speakers.
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BEL 1001 Mk-V (monoblock config), New generation Krell (post Dan D.), Goldmund (Monoblocks) driving Thiel 7.2s, Halcros driving big Wilson’s, and my current BAT VK-255SE is not too shabby.
ricred1 asks:
How do you isolate the amplifier? It's a system and every component, including the room impacts the sound.

Well the customary method is you disconnect it and swap it out with another amplifier. Just be sure to swap only the amp. You must use the same power cord, and cables, and cones, and even the same fuse if an aftermarket fuse is involved. Otherwise if you change the amp and the power cord, or cables, or anything else, then you will never know for sure how much of what you're hearing is the amp or something else. Changing only the one component allows you to hear differences due to that one component and that one component only.

Not only amplifiers, but every other component as well. That is how we do it. It is in fact what every review ever written is based upon. If you want to learn more about this and other essential elements of audio I highly recommend Robert Harley's book The Complete Guide to High End Audio. 
Luxman 509X. Incredible. Do not WANT to hear the M-900U/C-900U which is the Luxman combo that is appreciably better than the 509X. Supposedly the 509X is 90% of this top combo;

The engineering that went into the 509X receives maximum applause from me. 

+1 millercarbon

Someone posted a thread titled the best sounding integrated you’ve ever heard and akg_ca was somehow able to provide an answer, sans the unnecessary diatribe.

Best solid state amp I’ve heard was a Goldmund.
Luxman m900u is my favorite so far and one I hope to get in 6 months. 
second on the M-900u over Dag S250 which i recently owned. tube was Ref 75se. the luxman was superior to the other two imho but would be extremely happy with any of them
Pure SS Musical Fidelity AMS 100
Ayre VX-R Twenty
Vandersteen HPA-5 if you have powered sub or steens

but as Beetlemania said you should consider hybrid like Aesthetix and IF you have powered sub the Vandersteen HPA-7
just 5 parts in signal path, liquid cooling for perfect bias, no emitter resistors, floating ground, built in HRS isolation, the list goes on..... 
Spectral 50th Anniversary, and it's not close. By far the fastest, least distorted, I've heard, driving Alexia 2s, with Spectral's cd player as source, DMC30SV preamp.
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1.  I also highly recommend Robert Harley's "Complete Guide to High End Audio".  A consummate guide.

2. I have not heard many of the fine SS amps alluded to, but I can isolate the impact of the new amp in the system as I replaced my excellent Accuphase E550 with the Dagnostino Momentum driving Sonus Faber Amati Homage Anniversiers, and the difference was dramatic. A super clean fine-grained signal, what my wife describes as "pure", That may be something you want to audition if you have speakers requiring current.

I do really like listening to the Ayre MX-R Twentys as well.
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 

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.
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.
@dpac996 You are a lot smarter than me. I went to audition the 509x and liked it a lot. The c900+m900u were both sitting there unused and I gave into weakness and asked to switch the speaker cables onto the separates. Big mistake for my financial well being. I am buying the m900u but not sure about the c900u.

I have read online or heard back from users and dealers the following to use with the m900u:

* c900u it the best match for the m900u
* Mola Mola Makua + m900u is better than with c900u
* Linn preamp is a great match with m900u
They replaced a Levinson 333, and in my system they are about as good as it gets for me.My speakers are Shahinian Hawks, I believe 89db and they drive them with ease (4 ohms as I recall but don't quote me), ARC pre, PS DAC/Transport, Magnum Dynalab 809 Internet Tuner and PS P12. Minor tweaks to power cords and thats it. Blows away the Levinson, again, in my system
Bedini 25/25 is still the best I’ve heard in any of my system variations over the years. Still have mine purchased new. I have a Bedini 100/100 amp as well. Not quite as good, but close for when I need more power. Many other amps and components have come and gone but I won’t let the Bedini amps go.