To Bob Latino and/or others: On Tubes Asylum I asked a question as to which tubes in the signal path affect sound the most. I'm trying to learn about tubes and was trying to get at: "if you do change to "warm" tubes in the line stage (again an example) do you essentially change the sound that had been "managed" in the phono stage to that new warmer sound; or do you keep some of the previous and just add some features of the latter tubes?" After various answers to my questions I think I understand, much better now, how tubes affect sound.
In any case, I believe I had understood that the phase splitter tubes in the ST-120 amp don't have a major effect on the sound (or perhaps it's less than the middle voltage tube) so one answer from a poster surprised me. He said: "From my experience with a PP amp, the phase splitter tubes are very very critical to the sound."
I still have a long way to go in understanding so need more help about whether the 12AT7 phase splitters in the ST-120 are crucial or not?