I looked into that amp a little a while back. There are some pages on the net dedicated to modifiying and improving that particaular amp. It is supposively designed by a famous amp designer, and the tube sockets are actually chassis mounted instead of mounted on the PC board, so it is very good as a project amp. Of course you could always read reviews at harmony central........... Do a search for "G40V mods" and you find some good stuff. One page even goes into the outpus of each stage in the amp..... quite interesteing - I'm just oo lazy to look it up for you!!
Oh, yeah, but for what its worth, I've never actually played one, although I do want to try on out!!