I believe I have a JJ or JV tube in it at the moment, something like that. From what I remember it was an improvement over the ruby that it came with. Is there anything even better? How do I know I should replace the tube? It sounds great as is, but if the JV was an improvement, maybe there is something even better. I think I read somewhere the EV gold or something was great. Thoughts? Im mostly playing punk / rock style sounds for now if that matters. I've read over the extensive tube thread, and I don't think I have any of the symptoms of a bad tube. But I have used the same tube for over 5 years and I push it pretty hard most of the time. So who knows, maybe I should just buy a nice tube and try it out. Another thought is I only use about half of my available gain on my amp, is there any advantage to getting a tube that has lower gain? Differences in sound vs a hotter tube?