Best 300B tube

What driver and input tubes does your MkII use, and what specifically are you using in those positions?

My early Audion Silver Night used 5687 and 6922 and they helped a bit to tune the sound.

DeKay

Hi, same driver and input tubes. I replaced them before with a NOS Mullard (1962) and a NOS Sylvania (1960). It was an upgrade of course, so then I went for the 300B tubes with the same goal.

OK:

My favorite power tubes were (by far) the St. Petersburg Svetlana's (however they rarely lasted for more than 3-5 hundred hours in the amp).

JJ's were my least favorite tried (SS sounding).

The original Chinese 300B's were similar in sound to later (70's?) production WE's -w- screened Yellow graphics on the base, though the WE's were better. 

I ended up using similar (to you) signal tubes...

-late production Blackburn Mullard 6922 with dimpled disc getter
-Sylvania GB 5687

If I were to obtain another Silver Night I would probably go with the PX300 GL's (that you already came up with) along with the Mullard/Sylvania signal tubes.

My opinion of the GL's is based upon the online reviews that you most likely based your pick on, so no big whoop there.

Anyway, looks like you are aiming for the same warm/rich sound that I was.

I paired the Audion with a pair of Reynaud Twin MkII's and it was a very nice organic/3D sounding setup.

DeKay