Lets put it this way, just recently I sold my Krell amp that doubles its load down to 1 ohm for a whopping 1600 watts per channel. Upon installing the Innersound, cold dead out of the box it literally blew the Krell out of the water in every way. Musicality, bass, high frequency extension, transparency, effortlessness, soundstage you name it. I would never have believed it had I not heard it but it was there in spades. To take it a step further a friend was over who has Krell 650 MB's and he and I both thought the Innersound was more comparable to a 600 FPB or at least 350 MB's. This amp is a ridiculously good deal. To answer your question there are no other amps that I know of that are designed specifically to drive electrostatics like this.
Bottom line go for it. You have nothing to loose as he has a 30 trial offer and will pay for return shipping if you don't like it, if memory serves me correct.
routlaw