Best Sounding used amplifier under 1000???

Adcom 5803's are nice

I agree, Bryston is a great first choice. Also consider the McCormacks, excellent sound for the price.

The Anthem Amp2 is a great sounding amp (Hybrid design) and I've seen it as low as 800, but more average of $1k.

Bryston is good stuff.
Marantz MA500 or MA700 rock.

a rogue audio 88 amp can be had for around $850 used, and can be upgraded to magnum status afterwards for about $650, so down the road you can take your amp to a new level with upgraded caps, valves, etc (and the differences are not subtle imo). also, mark o'brien at rogue provides excellent customer support. i currently drive paradigm monitor 7 floorstanders with an 88 and am very pleased. the mon 7's will be rotated out this weekend for spendor s100's. your studio 80's should mate well with the tubed rogue. at 70watts ultralinear and 35watts in triode, this does not measure up to the 200-250 watts per channel, but why insist on 200-250 watts per channel? are you not interested in tubed amps for sure? if you have any interest about tubes, the rogue deserves a listen, i think it will be more than sufficient to drive your speakers. you owe it to yourself to listen to as many amps now while you are in the market to purchase one, if onnly to know a little more about what is out there. and you get you feet wet with valve amplification at the same time.
just my 2 cents fwiw

Conrad Johnson MF-2100 now on Agon @$750. It is 100wpc. The MF-2200 is 200wpc and should go for about $1000 used. Check out the reviews at audioreview.com. You can't go wrong with CJ