small news is better than no news, I scored a little 40W push-pull valve amp on a local second hand site for 50€ and will use it as an intro to debugging valve amplifiers with the help of a book from publitronic (modern valve amplifier design) to gain better knowledge of how it works

once I have a better hand at it I'll make a small push-pull of EL36 like the one at http://www.guitargear.net.au/discussion/index.php?topic=34435.0 and try to drive it with the PAM module

once this is OK I'll adapt the PFC stage of a DELL server PSU

the current process is to trace a 1kHz sinus along the signal path of the 40W amplifier and find the source of an anormal clipping at the input stage