This diabolical amplifier is available on eBay for a very cheap price. There's a good reason it's cheap. It doesn't work. The first stage doesn't work, the 2nd stage had a fake transistor supplied which doesn't work. This had to be redesigned to get to work and it still doesn't work properly yet. I think the MOSFETs are wildly mismatched so they need changing, there is too much distortion. The extra time spent on this is particularly frustrating, as I may as well have started making a PA from scratch on copper clad.