I guess on different days, Ken has different opinions.
He has told me that Telefunken smooth plates are the best he has heard in his preamps. I think he hasn't done much experimenting. There are lots of tubes that will vastly outperform Telefunkens in my CAT Sig MK2. I am currently using Amperex 6922 pinched waist and Sylvania 5751 blackplate 3 mica square getter tubes in the pre. This combination is the best I have found (lots of rolling) and very expensive. Almost anyhting will outperform the Sovtek 6922 that is the stock tube in the pre. There are lots of tubes that will outperform the EI 12AX7's. If you try the inexpensive American tube types you will find better tubes than the stock tubes.
Bart
He has told me that Telefunken smooth plates are the best he has heard in his preamps. I think he hasn't done much experimenting. There are lots of tubes that will vastly outperform Telefunkens in my CAT Sig MK2. I am currently using Amperex 6922 pinched waist and Sylvania 5751 blackplate 3 mica square getter tubes in the pre. This combination is the best I have found (lots of rolling) and very expensive. Almost anyhting will outperform the Sovtek 6922 that is the stock tube in the pre. There are lots of tubes that will outperform the EI 12AX7's. If you try the inexpensive American tube types you will find better tubes than the stock tubes.
Bart