What PI tube do you use? Why? What differences do you hear (feel free to be as descriptive as possible). I just buttoned up an amp build, essentially a blackface type Super Reverb... It currently has a 12AT7 tube in the phase inverter socket, like the old ‘60s Fender schematics call for. Sounds big and clean, but not necessarily as warm or dynamic as some people prefer (opinions being subjective and all of that). I’m primarily using this amp for vintage cleans (soul, surf, country, rockabilly), so I’m not necessarily interested in grinding gain (I have plenty of other amps for that).