Amp For Sopras

You will probably get a million different opinions, so I will give you my opinion based on ownership of a few different amps. Both amps I am recommending are not bright at all. They gave me many hours of non fatiguing music enjoyment with great detail, without sounding clinical. Smooth is my best description.

1) Atmasphere Class D mono amps. 100W should be more than enough to drive your 8 ohm speakers. They run very cool (if temperature is an issue) and have a tube like warmth.

2) First Watt SIT-3 (only used available at this time) or maybe better for your 89 dB sense speakers and within your price range is the SIT-5. I owned a SIT-3, but believe the SIT-5 is a mono amp version with more power. Built by Nelson Pass (of Pass Labs) and you get a real bang for the buck compared to the price of the Pass Labs amps.

Both are high quality builds and have above and beyond customer service. Questions usually answered by the builders themselves, Nelson Pass and Ralph Karsten 

Parasound amps are pretty warm sounding. The JC5 might suit your needs. 

@OP The Sopra is efficient but it is has a difficult modulus of impedance and the combination of that and its tendency to brightness does not make it well suited to tube amps. Passlabs Class A amps would be a good match in terms of their ability to drive difficult loads.

I guess we have different ideas about what qualifies as good sound.

LOL

I run Atmasphere Class D's with my Sopra 2's and can't see myself using any other amps. Cool to touch, smooth, silent when left on and detailed as. Never understood the brightness people claim Sopra's exhibit because I don't hear it and I'm in a 9x13 tiny room.