I have a very tight range to set my preamp volume (drive control I guess) on my Sunn 1200S head, no matter what bass I use, where I can't clip the preamp. I check this every time I plug in. If the "light" goes even slightly to "red" the speakers will distort. If I can find that extremely delicate balance where the light stays green no matter what, my speakers will not distort or fart out without me being way way too loud, so my question is thus: Is there a preamp tube, 12ax7 I believe is what is in there now, that is "better" at just warming up the tone but is more resistant to overdriving and clipping the preamp? I haven't replaced the preamp tubes in at least 3 years....does that have something to do with how much input they can handle before distortion and overdrive get through to the output stage of the amp? My ideal tone is totally clean with no overdrive unless I really dig in finger style extremely hard which there's only a couple of tunes we play that are even close to that intensity. Any suggestions? The basses I have are passive, active 9 volt, and active 18 volt preamps. They all have the same issue..it's almost impossible to dial in the preamp volume without clipping it....the "sweetspot" is just that...an extremely narrow range....like between 2 and 2.05.....2 is too weak a signal and 2.05 is too strong. Help?