I recently picked up one of these little guys, and was happy with it until it died on me. I am not sure if it is the tube or something else that went out on me.
I had about 40hrs of burn in on it and was absolutely pleased with the results. I then noticed two little knobs on the board and did a little research. I found an article on how to set the bias on the amp and I think that's where it all went wrong. The tutorial showed where to check the voltages, and said to set them to 16.5v. I raised the left one from 10.2v to 16.24v and the right one from 8.9v to 16.25v. I then rechecked them about 10minutes later and they seemed stable.
About 10mins after double checking the voltages I heard a nasty crunching noise then the volume cut out. I turned the unit off and let it cool down before I re-assessed it. The bias settings were still at 16.25v on both sides, but all I got was this odd buzzing and hissing sound. The volume knob didn't seem to do much in terms of turning up the volume of the music, and adjusting the knob during the waves of static had no change in the noise.
I shot off an e-mail to Bravo asking if they have any sort of warranty or replacement for the poor little guy. I had it just over a week before it died. I explained the symptoms and am hopeful for a response.
I wish I had more experience with circuit boards and how to test things and knew what symptoms might mean what but I really have no clue. I can get audio samples when I get home and post audio/pictures if that would help anyone help me figure out what is going wrong with my poor little amp.
Other than the thing dying on me, I was absolutely blown away by this little amp. At first it was not very impressive, but after 20hrs of burn in it was really starting to warm up the sound, and all the crunchy guitar goodness. After I adjusted the bias I was enjoying my big grin listening to my music until horror struck my face when it died.