Pure Class-A Amp under $2000 (USED)

If you can find a refurbished Sumo The Nine Plus, it's a great sounding Class A amp. I wouldn't buy one though unless it's been thoroughly updated with new caps, etc. by a professional service tech. It does use a cooling fan so be aware of that.

Most “class A” amps are not “pure class A” because they are extremely inefficient and get very hot, even with massive heatsinks. They are basically space heaters. 
 

Even amps like the Pass XA25 (50 watt class A envelope) are not pure Class A for this reason. 
 

Also, it’s my experience that even high efficiency speakers can really benefit from the headroom afforded by higher power, >100WPC amplifiers. It isn’t so evident in a vacuum of course, but power a 90db sensitivity speaker with 50 WPC, then power it with 250 WPC and this truth becomes very evident, especially at lower volumes. Just food for thought. In many cases one is better off using an amp that is heavily biased into class A, for a dozen watts or so. 

Try looking for the Forte brand . Made a Model One that was 50 watts and later upgraded the line to a Model 4 (Fifty Watts ) and then 2 Monoblocks ! Don’t recall that model # . Had the Model 4 loved it but parted with it going up the audio chain ! The thing about a Class A amp is that most of them generate a lot of heat so take that in consideration! Good hunting in this crazy hobby !

I recently sold my Classe Audio DR-8 power amplifier ("Pure Class A", hence the name) built in Canada and designed by David Reich. It served me very, very well with Vancdersteen 2c models and most recently with Magnapan LRS. I replaced it with a Schiit Vidar (not class-A). I am still considering the wisdom of the new v. old amplifier but class-A was very satisfying for me for a very long time.

No one is mentioning Plinius SA 100 ? This amp can even powered my Andra Eggleston and it’ redefine Class A category per Stereophile review.