Hey All! I'm still a bit new to the Marshall Forum, but already I have seen quite a bit of discussion regarding the selection and operation of power amp tubes. But... I would really like to get some feed back regarding the selection of preamp tubes. I rarely play out, and quite frankly seldom have opportunity to turn my TSL122 up past 1 or 2. I am aware of the fact that because of this, I will be getting most of my tone from my preamp section, and not from the power amp. That being the case I would like to know more about how preamp tubes effect my sound. I play mainly classic rock ranging from AC/DC to Def Leppard. Clearly I love distorted guitar tone, but I also love the way my TSL122 sounds on the clean channel. So... What I am hoping for is feedback from you more experienced members of the forum regarding such topics as: How will different tubes change my sound to better suit my style of playing? What tonal qualities do different preamp tubes have? What is a good starting point for finding the right tubes for me? Can I "mix-and-match" preamp tubes? How long do preamp tubes last? How often should I replace them? Please, do share your thoughts on this subject. I am eager to know what your experiences have been. Thanks in advance for your responses!