I'm looking for more information on using 12AT7 12AY7 12AU7 preamp tubes in my single rectifier - solo 50 - series 2. From what I can tell it's ok to use these tubes except for the v3 position. My goal is to get a little less gain and more adjustability range out of the volume knobs. With 12AX7's the vol knob is sssssssoooo touchy, going from 1/4 to 1/3 volume is just an insane amount of volume difference. Will I damamge or hurt my mesa head by using these tubes? - thanks guys