I have a Mesa Boogie Buster 200 15" combo. All tube,6-6L6 Mesa tubes, and 3-12AX7 Mesa tubes. It sounds great as it is, but I want to change the tone a bit. Right now it sounds like a tube amp, but alittle too clean for me. I can't really get it to go into saturation without turning the volume and master up way high. By that time the whole sound is just blown out of whack. I DON'T want way too early saturation like some Ampegs, but I DO want to be able to get some breakup earlier than it does now. You know a more thicker "greasier" tone. Do I need to change both the preamp tubes and power tubes? Or will one or the other get me the tube sound I desire? I tried a Sansamp also, but it just doesn't help the sound. It just added noise and mud. I think I want to get the sound with a tube change. Suggestions please? Once again, would the preamp tubes do the trick, or power tubes, or both?