Mini amp with passlabs / tube like sound

First Watt Sit 4 $5,000 - Nelson Pass designed, all solid state, brilliant amp if you only need 10 watts

A Rega Io would fit the bill. Lower powered, sweet sounding solid state amp. You would be surprised how good it is. 

I have a similar setup speaker wise, and I have been using the Schiit gjallarhorn power amp. It is very neutral and at $300 it's a real bargain. I wanted a little more power so I bought a second - you can run the L/R outputs together to double the power (8 ohms). I believe the circuit topology provides a class A'ish sound, and the amp is marketed as a near-field device. Solid state, inexpensive, made in the USA, 5 year warranty. I would shy away from the Chinese bargains on fleabay.

Pass Labs XA25

I second the rec for the Pass XA25. Hard to do better if your speakers are at least 90dB in sensitivity. 
 

I don’t own one any longer but have fond memories of this amp, probably more than any other. Might buy one again someday.