Amps which are Great, but either Unknown or Underpriced

Sunfire amps

I think the H-Cat both amp. and
prramp. are the best kept secret in
audio. 
Going for 6k (the present 10X series
pre. & 11k for the amp ).
You can find them on the used market
for less than one forth the price and 
then have both units upgraded for 
4K. by H-Cat. and be rewarded with
a non fatiguing organic sound.

Other amps. Audio Research Classis
30 and the Lectron JH-50 .

http://hephaestusaudio.com/forge/hma-harpocrates/

I like these. Plenty of solid power for my Ohm 5000 speakers.

Anthem 225 Integrated Amplifier. 

N

Nuprime (many of the principals used to be Nuforce).  Excellent sounding, small, and the newest ones Ref 20 and the MCH-K38 are at or near the state of the art in sound.  They have several different amps that allow you to pick the one best suited to the sound you want.  Those two amps are both 400 watts per channel at 8 ohms.  Other amps have less but still significant power (over 100 watts/ channel).  The 2 amps mentioned have the best sound of both tubes and solid state.   The price of the MCH-K38 is just under $3000 new.  The used Nuforce amps are selling at very attractive prices.  The less costly Nuprime amps sell new for well under a grand and are still very good sounding amps.