At the rate that I am using my Bass 400, I may have to retube before long. It also doesnt help that these are the same original tubes that have been in there since 1982. I rehearse almost every day for 1-3 hours. It might not be a bad idea to have replacements on hand since this is my only amp currently. I have heard good things about JJ's tubes. Anyone have experience using these with Mesa stuff? Should I consider some type of hybrid re-tube with different stuff for the 4 preamp tubes vs power tubes. I am not interested in bass distortion, so this isnt a factor for me. These days I am playing in a progressive-alternative rock band. We go from almost jazzy/lighter stuff to the occasional heavy grind.