I've always wanted to try a Western tube equivalent of the 6S45P in my Mainline. There was this one time PB said that the pentode E55L (triode connected) might just sound good in Mainline, someone just needed to try. It would involve some serious surgery though. In the collection there's both US Amperex New York and Mullard Mitcham factory made E55L. But the major work needed for the magnoval socket held me back all this time. It's the most left one on the line-up picture below. On the right you see the dwarfed 6S45P from the Mainline.
Recently another closely related valve, this time from Telefunken, found it's way into my collection (in the middle in picture). This is a triode from the 60's that equals or even surpasses the 6S45P performance named EC 8020. Fortunately the surgery needed for this tube only involves changing the tube pinout at the socket. It's close to plug and play! Be sure to add grid stoppers ( appropriate value) to each connecting pin as high transconductance tubes like this tend to oscillate.
How does it sound? Well, it's the known Mainline sound to me. No angels singing in my ears or anything. And Mainline sounds great! It's the best sounding amp I own from the technical point of view and now comes with "the queen of triodes".
