Bricasti Design. They are the most accurately musical amps I have ever heard, and I have listened to others at 10x the price.
Do not let the power specs fool you as they are extremely underrated. (After a discussion with owner Mr. Zolner he mentioned that at full published power output, the amps are only outputting 25% of their possible output which explains their extremely low distortion figures.) I have never heard (with the exception of Boulder) a more effortless presentation. They would make any hard to drive speaker sing!