The amp is very silent even when the high gain mode is engaged, until the tube goes microphonic, which is very soon after it is engaged or with a couple of tubes, the tube went microphonic the second I turned the hi gain on. Then there is insane amount of hiss, and even some weird overtones when I am playing. And the fact that when I tap the tube after the amp starts hissing, and it amplifies the tap, it's pretty clear on what's going on.
It is not that audible when the hi gain-mode is turned off, but when it is on... Nearly as loud as the playing itself!
I have owned my fair share of "high gain"-amps, like a Peavey 6505, Mesa Single Recto, Marshall DSL100 and the Triple Rectifier, and the guy has the nerve to say that the super loud hiss is part of the modern high gain amp personality, makes me a sad panda
So, I think I will visit the local store on monday and start a discussion concerning a new Invader.