Bogners website says attenuaters are ok with the Shiva. So I hooked up my power brake correctly triple checked. 80 watt Shiva clean channel volume 12 o'clock. Master volume 12 o'clock. Power brake minimum attenuation. Turned on the amp and it sounded freakin awesome. Became a different amp, notes just bloomed, I was amazed, lots of touch sensitive overdrive, everything I've wanted in an amp. After 1 minute I blow an output tube. I had a spare pair of SED's bought as a matched quad, put em in and turn on the amp. Again after 1 minute, another blown tube. The power brake was on minimum attenuation, amp volume settings on moderate. This should not be stressing the tubes too much I would have thought. Some time later, new set of tubes, and I borrow a Hot Plate. This time I play for about 10 minutes without blowing a tube, but I turned the amp off cos I was scared of blowing another tube and I didn't have any spare. So what was going on here? Are power brakes harder on tubes than a Hot Plate? Everything was definitely hooked up correctly. I would love to run the clean Shiva through a hot plate for just a little bit of overdrive, but I need to be confident I'm not gonna keep blowing tubes.