For anyone in search of tones that stir the soul and release the imagination of the player...you've GOT to go Tubes!

As for the powerbrake comment Lao_Tzu... those are not just a metal case and a potentiometer. A powerbrake (by any name) is a power soak, something like a sponge and it is built to put the EXACT SAME load on your amp as a given speaker would. It works in combination with the connected cabinet(s) to provide a constant and even load on the amp head. Therefore your amp should never be heating up simply because you've got a powerbreak hooked up providing a heavier load. However...you ARE cranking your amp up and a tube is no different than a motor...the faster you run it...the quicker you're going to have to go to your mechanic!

I have a Dr. Z Stangray running through a Dr. Z Airbrake to a 2x12" open back cabinet (with celestion alnico blues). The amp is rated at a conservative 30 watts and I still use the Airbrake even on-stage at small to medium sized venues.