I.AM.D V200 Full Digital Amplifiers
Not so great with USB or spdif input, excellent with I2S connection, and even better in bi-amplification.
Modification to connect I2S signal is explained in this thread (page 7 and 15, for later models): http://www.diyaudio.com/forums/class-d/280228-i-am-d-v200-fx-audio-d802-optimisation-tpa3116.html
I tried two other FDAs: QA-100 and D310. The V200, with the above mods, is the best!