I completely concur with everything jcarcopo said about Art Audio amps. My Carissa was used with a speaker that had a 12" woofer and 12" passive radiator with a 3.2ohm low in the bass. That woofer handled everything from 700hz down and the Carissa pulled all the music from it and showed it who was boss. Besides driving the speaker correctly it was also one of the sweetest sounding amps I've heard. Unbelievable tone, detail, resolution and dynamic.
I don't usually gush about gear I have owned but any chance I get I'll sing the praises of Art Audio amps. If I had the means there would be a new Art Audio Carissa in my system tomorrow.
Cheers,
Scott