I'm trying to find the tone I want from this amp. I have the 4X10 version. I like pretty much everything I've gotten so far, but I haven't found that one tone I LOVE yet. This is the amp I gig with simply because it's beat up and is built like a tank. I wish I could get an "overdriven" tube sound out of it. I've tried turning the volume all the way up on the clean channel, but the sound doesn't change too much. It gets "thicker," but it never is on the verge of breakup. I've also tried putting it on the lead channel with the pre-gain turned to right on the edge of clean and dirty with the post-gain turned all the way up. In both settings, I use the Master Volume to control the overall volume. Is there a way to get this amp to do the "on the edge of break-up" sound? Would this require a tube change? I use my pedals to get all the gain I need, but I just feel like there's something missing without the amp being almost broken up itself. Speaking of tube changes, have you guys upgraded your at all? What about speakers? I feel okay with the blue marvels in there, but I feel like I could do better. I'm looking for a 15" extension cabinet too as I feel like that will greatly improve the tone. Any ideas?