used power amp under 1500

@parkergetdean I am not sure if you said Schiit gear was not your preference. Another amp to consider is the Schiit Aegir v1 at 20-watts in Stereo via RCA. If you buy 2 in mono block form factor, then you get 80-watts via XLR. This is Class A.

I was listening to my used $400 Aegir v1 last night with my RAAL SR1a headphones and that thing was excellent. I have had amps costing a lot more than that on this phone and I kept the Aegir v1. I think the best for this phone is the new Vortex amp at $10k, I am sticking with the $400 Aegir v1 connected to a Schiit Saga 2 preamp (wow, for $279).

The newer Aegir v2 monos gets you over 100 watts Class A. Though I read that the Aegir v1 is slightly warmer and better suited for my bright phones. I have not used the Aegir with my speakers because I need a lot more power.

The Aegir gets compared to the First Watt amps. 

BTW - on the SR1a I use a $12k Imersiv D-1 DAC. Those 2 very low-cost amp and preamp scale nicely with great gear, such as the D-1.

What is the efficiency of your speakers? How many db at 1 watt into 8 ohms? 

For $1200 you can buy a brand new Audio By Van Alstine NP1 power amplifier, which is very conservatively rated at 55 wpc. It uses AVA's new nesting architecture and it's received several excellent reviews. 

The PS Audio S300 is super and can be had for about $1000. Can't go wrong with that. 

I would lean towards a well made super amp that’s a bit older.   Mark Levinson, Rowland, krell, classe, Bryson, pass labs, etc all made 100 wpc stereo amps that if you’re lucky come in under 2k.  
 

im running a vintage pair of levinson 20.5 mono blocks that had been lightly used.  They sing like the 25k amps they are.  Cost me 2250.

anyway good luck. 

A friend in my audio get together circle was looking for a new amp and settled on this company.https://www.buckeyeamp.com/shop/amplifiers/hypex/ncore

I heard these amps and was very, very impressed. He does his homework and stated the customer service is great. Well within your budget. I think he bought the mono amps.