I was made aware of this board via a German diy audio site who nick-named it the Gremlin. It received glowing reviews so I decided to give it a go. I have been using the amp for about 14 months and can report back that it exceeds expectation. Its unbelievable what it accomplishes for the price. The sound is huge and detailed. I follow forum advice and run it at 36V. People reported that higher voltages result in a 'harsher' sound but I can't comment. Although the amp is billed as 2x500W, in reality (8ohms, low THD) its more like 90W. I use this in conjunction with a cheap 6J1 buffer/preamp and couldn't be happier (ymmv).