A friend of mine has one of the older valvetronix amps that currently isnt working, he gave it to me to try and figure out whats wrong with it.
In our first conversation about it, he told me that while he was playing it the sound suddenly stopped, no fade, maybe a little crackle, but when you pull the cable out you hear the typical noise that you would normally hear. Ive opened it and cant find anything obviously wrong, I figured there must be some guru on the internet who can tell me whats most likely wrong, or at least what to look for. Everything powers up fine lights are on, and ive obviously tried it with multiple cables and guitars. Any help is much appreciated.
I have a VoX AD30vt. Same thing just happened to me, turned it on and got no sound. I fiddeled with my input wires etc, to no avail. I then fiddled with the inputs into my Cry baby, and then it started working again.

Sorry if this didn't help.

Also, i know i've had to fix my input 'hole' into my amp a few times now. So i dunno whether that's faulty?