used power amp under 1500

McCormack DNA-1 has my vote plus it’s upgradable 

Classe Audio made some of the best power amps back in the day (‘80’s-‘90’s).  Most are available in your price range now-a-days… look for a DR-8 or DR-9, both are in the 100 Watt range, and will drive any low sensitively speakers, and sound equal or better then many amps costing $5k-$10k . Check out TAS reviews that rave about their amazing sound… almost tube-like for a solid state amp.  Build quality is second to none.  I bought my first DR-8 brand new in 1990, and last year I bought a 2nd DR-8 on the used market for less then $1K, now I’m running both in mono, the sound is astonishingly good.  If you can find one of these, you will be set for years to come!

@parkergetdean another vote here for the Marantaz MM7025.  I use it to drive a pair of Focal Aria 926 speakers and can drive it to audio levels I am quite uncomfortable with.  I have played a lot of the test tracks on my system that are prevalent at the audio shows and to my ear it passes the test.  Since that amp has been out awhile you can find them used as well, I got mine on this site for $500 from a fellow who was upgrading to a 200 watt amp.  

@patrickalston Bryston no longer offers Back to the Future. 
 

Op - if you go with a Bryston used, Bryston will go back to the ST series for repair. The wont repair older amps for lack of parts. My local tech has parts.
 

+1 on Bryston! My 3b is still running fine, 45 years now!

Another positive vote for Aragon, either 4004 or the newer 8008. I bought a new a 4004 for about $1,850 in 1992 that I upgraded to a used Krell KSA-200S (that retailed new for $7,500).The Aragons double power into 4 ohms so 400wpc. I see your speakers aren’t efficient at 86db, but I doubt their impedance drops as low at my Martin-Logan electrostatic hybrids. I still own the Aragon 24K preamp with optional phono (MM/MC). Never any problems with them. Both will be used as they were made by Mondial when they owned Aragon. The new Aragon lineup has a new owner and the 2 channel stereo amp is over $10,000. I would also consider a used Krell integrated such as a KAV-400XI OR KAV-500I which would drive them great and can be had for under $2K. The KAV series from Krell was designed to operate more in AB than the hot and heavy Class A amps; they marketed them as more affordable, especially for the home theater market.