Pure Class-A Amp under $2000 (USED)

+4 on the Aegir. I have one in my main system for my 88 dB 6 ohm Ohm 1000 speakers and it easily goes to my loudest needed volume (about 85 dB average) without strain. (Full disclosure, I also use a sub.)  And, I love the sound -- previously had a Bel Canto amp and then a VTV Hypex that were both higher wattage but didn't sound as good. 

Schiit offers a 15 days trial with a 5% restocking fee if you try and don't like. $40 to try it out (plus returning shipping) which is a pretty good deal. And, there is also a solid used market for Schiit gear -- you can use it for a year or two and not be out all that much if you choose later to move on.

There’s a minty looking Krell KSA 200 on Audiomart @ $2100

The Sonus Faber would like power, especially if you play loud.  Most Class A amps are small 30 W or less.  I had a Schitt.  Sounded good but not enough grunt.  You need an amp with some weight, a big transformer, etc.

There are several AB amps that would sound quite nice. Parasound, Anthem, etc.  Look on here or other places you will be set.  

PS.  I personally will always own a class A amp but high efficiency speakers make it easier.

If you’re fortunate to find a used Clayton Audio S50 while your radar is up I’d say consider yourself hugely lucky and that you jump on it ASAP.  50 and 100Wpc of sweet-sounding and pure Class-A power into 8 and 4Ohms, respectively.  Read the reviews of Clayton amps and I think you’ll find them quite special too.  Best of luck in your search!

https://www.usaudiomart.com/details/649787192-clayton-audio-s50-class-a-amplifier/

-50 on the Schitt Aegir

I had a pair and they couldn't handle the LSA Statement 10 which is a 83db 10ohm bookshelf nor a pair of Fyne F501 which is 90db 8ohm. Both amps would shut off at any music past 88db volume. Both speakers worked perfectly on my Sony surround receiver at volumes well past 88db. 

Per Stereophiles measurements and ASRs' (49w @1% THD and 23w @.5% THD) Schiit severely lied on their published specs for mono rating. When confronted with the above publications and when I requested my money back, I got no response.

Here's the tests