Prefered 300B tubes for Canary Amplifiers

I do not know how many tubes that you would require or your budget or how you define "premium." However, in my experience in my 300b SET, the best tubes are the Takatsuki TA-300b followed by the Sophia Royal Princess. Both easily best the Shuguang Black Treasures. I have not heard the "standard" Psvane or the Psvane WE Tribute or any of the EMLs or any of the less expensive Sophias.

Charles and I are on the same page, and we can only report our own experiences. When I got my Def 2 speakers, I first tried an EL509, then a 45, then a 2a3, and finally a 300b SET. . . the 45 and 2a3 SET with different manufacturer tubes. The differences were modest and often within the range of reproducibility and were totally dwarfed by the improvement using the Takatsuki TA-300b. "Stupid money?" Perhaps. They are expensive - now 2000USD per pair. (I was fortunate to have sourced mine from Japan a year ago; apparently, this is no longer an option.) However, many A'gon members spend more than that on cables, tweaks, etc. Other than price, the only caveat is that the reports and reviews have always been in either an SET or a PSET amplifier; I have not heard from anyone who has used them in a PP configuration. The Sophia Royal Princess are good second choice at about half the price; I would have been happy with them. . . until I heard the Takatsukis.

I have only listened to the white base Takatsuki TA-300b. As far as I know, the black base replaced the white base versions; and the white base TA-300b are no longer made. I have gotten different answers about the differences between them and would be curious if you know any details.

Can anyone estimate the longevity of a 300b in a "typical" SET?

Not sure how many watts are dissipated. I will try to find out. When I once asked Jarek (the amp designer) and Keiko (from Amtrans in Japan) the question of 300b longevity, they were non-commital. However, 40,000 hours!?! At this rate, my first pair is barely broken-in; my second pair will outlive me; and my plans to buy a third pair when I am in Japan in July are "stupid money" silly. LOL.