@tksteingraber I have put many tubes through my Cabernet. Keep in mind that sounds good will vary depending on what tubes I have in mt amp. When Mick built mine I had him put in a 6v/12v switch. Best thing I ever did. 12sn7 are much less expensive4.
Favorite 6sn7(ish) tubes in no particular order:
Raytheon 6f8g T plates
Sylvania tall plate 14n7. They aren’t the same as the 7n7!
GEC/Osram/Marconi b36
Ken Rad round plate 6f8g
Interestingly, to me at least, is that I haven’t really liked having the Sylvania so called bad boys or Tungsol black glass, round plate in my Cabernet. And, yes, they are actual bad boys with the right dates, construction etc. I do like the Tungsol BGRP as drivers in my push pull amp.
I have also had a lot of luck with single triodes with the use of adapters. Mick makes his Grange with 6j5. The 6/12j5 and equivalents, while rising in price quickly, are still good deals compared to the 6sn7 market. Here are some of my favorites:
Radiotron (from Australia) 6j5gt
Raytheon 12j5wgt
National Union JAN 12j5gt
Cossor branded 6c5g. There’s some debate who actually made these but they aren’t the GEC. Currently available from Langrex.
GEC l63gt brown base.
Fun fact, the 6c5 is a good substitute for the 6j5 and I got Mick’s blessing to use them in the Cabernet. The 6c5 is actually, literally, a 6j7 triode wired so it is possible to use that configuration with the appropriate adapters as well. Haven’t done that yet but I will soon.