http://www.diyaudio.com/forums/showthread.php?s=e80d7dd05f01fce38712d6956a3e4657&threadid=1989&highlight=digital+amplifiers
That link has a healthy discussion on the amps, with specific mention given to what tact is doing. If it doesn't work, go to diyaudio.com, click under the "digital" forum, then click "search" and then type in digital amplifiers and one should come up about amplifying an ESL with a digital amp.