I short out the speaker terminals while the preamp volume is up all the way as a demo at shows. In addition, I pull tubes out of the amps **while they are playing** and swap them from one channel to the other, with no ill effect or artifact at all. Is that what is meant by 'bullet proof'? or does that have more to do with what happens when you drop the amp?
bullet proof amp
I need a bullet proof amp to put into my shop where many people could use it,some not so careful, that can drive 4 speakers. vintage preferred.