It has been a journey for me to search for the "perfect" 6SN7s. I have 3 amps that use 6SN7s, and I tend to use GTAs and GTBs for driver tubes only. I have the following tubes for the gain stage and my summary is as follows:
Sylvania VT231s, bottom getters: clean, fast, accurate, and airy. My choice for classical music, but a bit thin for vocal music.
RCA VT231s, smoke glass: rich harmonics and sweet sounding, but a bit slow. It is great for vocal music, but not for complex classical.
Raytheon 6SN7GTs: nice sounding, but a bit too sweet for me
RCA 5692 Redbase: fast, rich, dynamic. It is excellent for Jazz and vocal, but not as good as Sylvania VT231s for classical music.
CBS 5692 Brown base: a tuned down version of RCA Redbase.
Ken-Rad clear glass: a bit too euphonic for me
Ken-Rad black glass: strong bass, but does not have the airy magic
Sylvania 6SN7GTs chrome top (not to be confused with GTA chrome top): my current overall choice, they are as fast and airy as Sylvania VT231 bottom getters, but have more sweetness.
Sylvania VT231s, bottom getters: clean, fast, accurate, and airy. My choice for classical music, but a bit thin for vocal music.
RCA VT231s, smoke glass: rich harmonics and sweet sounding, but a bit slow. It is great for vocal music, but not for complex classical.
Raytheon 6SN7GTs: nice sounding, but a bit too sweet for me
RCA 5692 Redbase: fast, rich, dynamic. It is excellent for Jazz and vocal, but not as good as Sylvania VT231s for classical music.
CBS 5692 Brown base: a tuned down version of RCA Redbase.
Ken-Rad clear glass: a bit too euphonic for me
Ken-Rad black glass: strong bass, but does not have the airy magic
Sylvania 6SN7GTs chrome top (not to be confused with GTA chrome top): my current overall choice, they are as fast and airy as Sylvania VT231 bottom getters, but have more sweetness.