Pure Class-A Amp under $2000 (USED)

Unfortunately, used $2k Plinius SA100 amps aren’t around any more. I believe people are hanging onto them. 100 watts 8 ohm, I believe 200 watts into 4. And flip the front panel switch to listen in A/B mode. 
 

They would drive anything.
 

These amps were some of the best available in 1999. Commonly available used everywhere for $2k. Their Mark III version was the finest Class A amp I’ve ever owned. But sadly today, those amps are gone. If you didn’t sample one in 1999, you truly missed out. 

An amplifier that runs in pure class A operation does exist regardless of what some may say. There are some amps that switch to A/B when pushed in volume but there were amps designed to run class A always.  A killer and very inexpensive class A amplifier is the Forte Model Four.  50 watts per channel and a killer of an amplifier. Sold by Nelson Pass under the Threshold company but the amp was designed by a Swedish Engineer who worked for Nelson during that time. The Forte Four was the 1st amplifier I purchased 35 yrs ago with a Conrad Johnson tubed preamp when I first entered this hobby. I picked it up in a Stereo store in Manhattan NYC. I sold it 1 year later and moved in the direction of tube amplifiers. I’ve owned since about 50 amplifiers, all extremely good and now listen mostly to single ended tube amps. Never forgot how good the Forte sounded. After 30 yrs, I’m so happy to be he owner of the Forte again. I own 2 now with all the Jon Soderberg upgrades. If 50 watts per channel will be enough, the Forte Four is not just a good amplifier, it’s a killer amp. If you need more power, Vintage Threshold has a good line of amps. Krell KSA series was great as well, KSA 100 Mk 2. Good Luck.

I'm a big fan of the SONY TA-A1Es integrated amp,   Built like a tank and sounds amazing, can't believe how good it sounds for the price.  I thought Sony did a terrible job of marketing this amp, it should be far more well known than what it is.  

$2000 is a tough budget for a good Class A amp. Your choices will be limited to older amps like the Krell KSA or the Plinius. The KSA are great amps but old which means you will be sitting on a time bomb. Rebuilding those amps will be expensive.  If you can wait and up your budget, the Pass XA25 is the current model and should drive your speakers just fine
 

Are you a DIY type? Nelson Pass has provided many amplifier designs to the DIY community. Anything from 5 W/ch up to 100 W/ch, all biased into Class A. I have built the Aleph-J (25 W/ch) which is based on the original Aleph series of amplifiers with J-FET inputs instead of MOSFETs. A very popular design is the F5 (25 W/ch) and the F5 turbo (50 W/ch). Both the Aleph-J and F5 were sold under the First Watt brand as well, but can be hard to find on the used market.