I've probably reached the end of the road for ideas on repairing this amp.
One channel prone to oscillate to fatally high levels.
Changed the dual FET at the input end of the amp stage
and seemed to cure the sensitivity to scope/ DVM probes
placed anywhere on the circuit - DC coupled,class B amp.
After 3 hours under test load the 2 output trannies fry -
anyone any ideas. ?

electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse

Nigel, Diverse Devices,S outhampton, England