Holy grail LOL. Ok ... they are pretty good.
Ok. Your sarcastic comment about Sylvania 6SN7-GTB/5998 is duly noted - and probably justified.
So I guess I will have to give you the true Holy Grail. It's Sylvania 6SN7-WTBs/6520s. And you can take that to the bank
The other day when I was discussing my 6SN7s I didn't give due credit to the WTBs because I hadn't listened to them in a long time. Been listening to them a lot since then. They are more than "pretty good"