not to mention $ $ $ $ but it IS an awesome amp. It's little brothers, the M1s, are just as impressive on a smaller scale.http://www.ddaudio.com
Digital Designs Z1. 3000w rms @ 12V @ 0.5%thd+n. Put more voltage on it (up to 15.8V) and it makes more. Dip below 1ohm and it really wakes up.
ma audio amps be the shi*t, don't see them mentioned much on the forums myself though but i swear by em.The new MA Audio Class X amps claim >93% efficiency. I think they still do their 4kw model.