:) Blasted, you plugged +4db into HI Z /Hi gain instrument level input?. Or was it a line level input?
I expect if you don't hear hum in the phones, it could be a level mismatch, toooo much gain. Try it on the line in's of someones stereo.

Sorry to hear about about your fire :( .

--Rick

Try running the direct output of a channel or an aux send to the Marshall. if the buzz stops, you know its the main bus on the mixer..

this probably goes without saying since you mentioned the 60hz hum by name - but make sure they're on the same ground circuit along with everything else in the loop.

not too long ago i saw the same problem arise when a signal conditioner somehow took a piece of equipment out of the loop that everything else was plugged into. and that was strange.

good luck.

scott sends . . .

Was it just the cab, or was it into an amp as well? I read somewhere that the headphone jack will work well with an amp's input, (cheap alternative to a re-amp box...) can anyone confirm this? I think Rick nailed it though, try patching it into a stereo.