Best Class A Amp under $2,000 used?

Sony TA-A1es integrated. 

Get a pair of clean efficient speakers and a good single ended tube amp as I recently did, and stop chasing watts…my current rig sounds better than anything I’ve had in my home in over 50 years of audio fun…it’s simply funner, and more dynamic somehow (everything I knew is wrong?). Watts SCHMATTS! Note I use a couple of powered REL subs for "under 40hz" duties so maybe I’m cheating a little…still…great sounding, more musical, and, dare I say, more realistic, is just a better thing to have as it’s better. Or as Hawaiians say, Mo Bettah.

There's a Plinius SA250 mk. IV for sale here now near your price range.  250W class A power and has a switch between A/AB operation so can operate at higher efficiency and less hot for non-critical listening.  Best of luck. 

It's pretty clear that the original poster has no idea what he's doing. But for the others:

Yamaha B-1. 1975-1978. Caused Levinson, Pass, and others to dream into the future. 150 watts pure and only Class A into 8 ohms at .1% distortion, more than 250 watts at 1% clipping criteria. Nearly doubled down like a perfect voltage source ( 4 ohms ~ 500 watts at clipping) . Mega SIT VFET's, super quick with 72 nanosecond rise time. I've seen a few sell for $2k or so but often need work. 

Very rare. Only about 50 made, I had a couple and wish I had never sold them. Specified as 4-16 ohm load capable, but I successfully drove the original Martin Logan CLX prototype- which was nearly impossible and only one cut above a short circuit (production models were tamed down considerably but never sounded as good). Also superb on Stax ELS-8x's, another rare and difficult speaker needing lots of power and load stability.

Issue here is if you blow a SIT, they aren't available anymore. New SIT's manufactured by Digital Do Main out of Tokoyo might work, but I don't know if you can buy them.    osobagary@gmail.com