What Amplifiers Have You Heard In Your System and What Amplifiers Will You Always Keep

Shindo Cortese (Sold but will buy another one someday)
Shindo Sinnhonia (Good but not even close to the Cortese)
Berning 300B Siegfried (Sold to a good friend and will always be my absolute biggest regret in this hobby.  He said he will never sell the amp back to me which I've begged him to do.  The absolute best amp I've heard.  An idiot friend who I trusted at the time said the Kronzilla was better which it was unambiguously not.  I was swayed by the aesthetics of the Kronzilla vs the more pedestrian Berning.  Rookie mistake.)
Berning ZH270 (Sold)
KR Kronzilla (Sold)
Rogue Cronus Magnum (Good drive and a fun listen)
First Watt J2 (Sold but will buy again someday.  My reference for a low power ss amp.)
Coda (Forget the model.  It was a friend's who let me demo it for an extended period.  Absolutely great amp.  Something I would consider going forward.)
Crayon
Wyred4Sound ST500
Bakoon Amp 13r (Freferred the J2)

There have been a ton of others, but these are the ones I remember.

Currently:
Kinki EXM7 (Still trying to decide whether it's a long-term keeper.  My sonic recall is that the J2 was more to my sonic liking.  Need to a/b the 2.  The M7 might be the high power choice, the J2 low power. choice)
Triode Labs 2a3 FFX (My low wattage keeper but want to hear a Whammerdyne)
Finale F 7591 (My bargain amp favorite and an absolute steal because of the bad 6-Moons review.  In many ways prefer it over my 2a3.)

Need to Hear but own the Vibe/Pulse pre-amp:
Tom Evans Linear A

Favorites by type:
SS:  J2 or EXM7
SET:  Berning 300B
PP Budget Amp:  Finale F7591

Favorite manufacturers:
Berning
Tom Evans
Nelson Pass

To put things in context, I prefer an immediate, dynamic sound with a large soundstage.  When I get that with good timbre and tone, it's a keeper.  

First Watt F5, J2
Monarchy Audio sm70 mkII (x2) 
 I like different flavors,what can I say?? 

VTL 450MKII.

All three of my Music Reference: RM-9 Mk.2, RM-10 Mk.2, and RM-200 Mk.2.

I started to compose a list of amps but the page refreshed or timed out.   Out of the numerous amps I’ve had over the years a few stand out.     B&K Sonata M200 monos...  great amps.  McCormack DNA 125 another great affordable solid state amp.   
VTL stereo 50.  TURD.  Sounded great when it worked.  Almost turned me off of tube amps.  
Best value. Brand new Anthem Amp 1 for $699.   Great amp, restored my love for tubes.  
Currently using Quicksilver Mid Monos.  Great amps,  Point to point amps that will take all the popular power tubes... for $1999 new?   Best value out there right now

Those will be replaced soon by a Toolshed Amps 300b.   

Had several integrated amps over the years. Have only had three power amps over the years. Primaluna Dialogue Premium stereo - bought new, and enjoyed for a few years and sold. Moved to Audio Mirror 45w SET monoblocks (driving EgglestonWorks Fontaine Signatures) - wonderful amps and keepers. Also have a used Van Alstine Synergy 450 that I got directly from Van Alstine (225w per channel solid state). What a great amp, smooth yet detailed, and an incredible value. Bought it as a backup, but running it with Fontaines now. It is a keeper also. 

Audio Hungary Qualiton X200 perfect for me.

Krell KAV250- I tried to convince myself I liked this amp.
Parasound HC something - not my thing.
BAT VK250 - good amp but I found it a tad on the dark side.
Forte Model 4 - great little amp. Wish I still had it.
Mark Levinson 331.5 - a friend let me borrow this but I loved it.
early Rowland amp - same friend let me borrow. OK amp.
Pass Labs x250 - exceedingly neutral sounding amp, for better or worse.
Primaluna Dialogue Premium HP w/ KT150’s. The winner thus far.
A bevy of integrated amps both tube and SS.
Would like to try a PS Audio BHK and Hegel amp sometime.
As far as what I will keep? I never seem to.

I have tried so many amplifiers in my system, too many to list and i have only kept two.Parasound hca3500-best overall amplifier i have ever heardSonic Frontiers Power 1-best tube amp i have ever heardFor my other systems i have found some other very good amplifiers.Harman Kardon citation 12accuphase 306vsoundcraftsmen a5002b&k stereo202 plustechnics setx100denon pma2000rsansui au717Haman Kardon 330bThese all sound good enough to keep for one or many reasons in a secondary system but i have twenty three pairs of vintage speakers so i have to keep a variety of amplifiers around to switch out and change when the need arises.

You know this is not going to be helpful to you....BUT And I'm not going into the reasons for "why I kept a certain amp".EXCEPT......  with my magneplanar 1.6's .....I went from ok (sound with nuforce9 v2 & v3's) pretty good....with the Magneplanars and then switched to an  Odessy Amp up grade from Klaus that was better with the maggies. But the Odessy's where just ok ...so I had to move to the Pass J2's because I was stupid and fell for all the marketing and on top of that I have no mind of my own......however  before I could evaluate the pass...I had to move  to a small condo and with different speakers  (Decapo 3a's ...the  Pass J2's was great....But again with no  mind of my own the big dog from Hawaii told me that the audiospace 300b's with the Reference 3a decapos were the cats ass....  He was right until one of the 300b tubes blew up on a
passage from the bassist ......sorry dont remember his ...oh yes now I do remeber his name it was very painful watching Christian Mcbride smoke on e of those 300b tubes.....Then my dad sent me ...bless his sole.....get ready for it...the McIntosh c22 preamp and the 275 amp all restored Mac gear from the 1965's ........it was great with the Decapos' but not very TRANSPARENT! 
so off it went to somewhere .....and then back to the pass J2,  the pass was still great. BUT I had an attack of upgradeitis so I sold the Decappos to a buddy and bought the OLN 3 prestige whatever/// They are very, very, very good with my new pass 30.8!!!!!
So I will never sell the 30.8's ever....oh forgot to mention they worked wonders with the decapos...too BUT NOT as good as the Audio Space amps.
Hey it's a long winded post that maybe I should have just said it's a journey with this hobby...and you are on a path that is best decided with experimentation......kinda like trying to decide who you are going to marry?? Sometimes it all depends on your circumstances and ohhhh cynical your bank account.

Or from a scientist perspective...speakers and amps are a systems problem😂

Best wishes
Charlie

Not an exhaustive list, but the highlights have been:

an early Bryston 4B (powered Magnepan Tympanis)

Pass Aleph 3 ( the Sea Urchin; powered Dunlavy SC-III speakers)

Jeff Rowland Concentra I (one of my favorites)

Accuphase 303x (recapped and upgraded; terrific amp)

Hegel h160 (excellent all around amp, and value on the used market)

GATO AMP-150 (current; excellent, very transparent amp)

the power amp section of my Kenwood Model 600 is very special

QuickSilver Mini Monos. Very sweet amps. 

Micromega M150
Ayre AX-5 Twenty
AVM Evolution A5.2
AVM Ovation MA 8.3s
Canor AI 1.10
Canor AI 2.10
Rega Brio R
BAT Rex 2
Art Audio Opus 4
Art Audio Quartet
Carver TFM 15CB
NAD C298
NAD M33
Naim MuSo
Naim Uniti Atom
Naim NAP 300 DR
Chord TToby
Rogue Audio Hydra
Marantz C510 Network Receiver

These are the amps I have had relatively recently that I have either taken in on trade or are demos.

I will never sell the Art Audio Opus 4s, Rogue Hydra and Carver TFM 15CB. The Opus 4s are my reference in term of sound quality and the others are old favorites.

I wish I could afford to keep the AMV MA 8.3s. Tough to justify $40K amps when you don’t need the power and they don’t fit in your space.

Only two of the amps on this list were not at all to my liking. I found the micromega to be far too bright. The BAT was also not to my liking and will leave it at that.

I am a dealer for AVM, Canor, Art Audio, NAD, Naim and Chord. I have no relationship with the other brands.

Primaluna PL2  first amp great starter soldVista Audio i84 second system amp good but sold
Decware Mini Torii  keeper had for 10 yearsGrommes PHI-26  second system keeper 9 years
Decware paired with Ref 3A de CaposGrommes paired with Klipsch Quartets

Bryston 3B-ST, 4B-ST, 7B-SST (all sold)
PeachTree NOVA 150 (sold)
Parasound A23 (sold)

KRELL K-300i (selling)

D-Sonic M3A 800s (keeping)
CODA #8 (keeping)
Benchmark AHB2 (keeping and my fav)

Sansui au-999
Harman Kardon 330c
Kenwood ka-3500
Audiolab 6000a

Love them all. Keeping them all.

Crown d-75 power amp. Waiting to refurbish then I'll decide whether to keep :)