I suspect they aren't driving the tube that hot, so dust shouldn't be too much of an issue (unlike some old equiptment, where the smell of heated dust greets you as soon as you turn it on). I, too, would like some information about the voltage /current capacity of this amplifier for different loads.
Looks like gain is 30db likely from the 12au7 (mu factor is 30) and some specifications are posted on their website:
http://bravoaudio.com/bravo2.html
Looks like gain is 30db likely from the 12au7 (mu factor is 30) and some specifications are posted on their website: http://bravoaudio.com/bravo2.html