Per Philefreak, I'd agree on the suggestion to try listening to some 2A3 SET amps, especially an amp like the Wright 3.5. But I would add that you'll be pushing the limits at 96db efficiency if you like listening at louder levels on some music. If you go that route I might suggest very careful speaker selection as you are only talking about 3 watts of power at that point. Those three wats are pretty magical if done right though. I can give you my own comparison of 2A3 vs 300B: I'd agree that the 2A3 does vocals like no other tube, but in a SET configuration, in my experience, it has come with what I might term a lack of fullness in the range. The 2A3 tube in SET is all about midrange and upper midrange. The lows are not a strong point with the 2A3. I would put that choice at the extreme end of selection in considerations, though if you truly do listen to 90% female vocals, I'd say it'd be an excellent suggestion as well, given the caveat that you'll be looking at different speakers. I do love the Wright Mono 10's which use 2A3's in a push/pull configuration to yield about 11 watts. This, to me, yields a fuller sound from those tubes, while maintaining that magic midrange potential. I'm not sure if there are other 2A3 amps that use the tube in that way, but it may be another choice to consider. It is closer in fullness to my 300B amp, while having a bit of an edge in female vocals (a bit more sweet and airy). In my 300B amp I would say it is a more balanced implementation of the strengths of SET and less of a sacrifice in any one.
As far as the overpriced WE 300B tubes, do keep in mind that they are by no means the only good choice. There are plenty of decent 300B's out there that you don't need to sign over your first born to obtain. Certainly the WE's are an outstanding tube, and I use a pair myself, but the more recent production tubes typically can be found for $400-800 pair and have a predicted lifespan of 10,000 hours. I've read a few recent shootouts and comments here that maintain that the newer Svet's and the JJ gold's are not far off the mark, and to some ears may be superior than the WE's. There's an abundance of 300B's to choose from in current production. Your selection of current production 845 tubes is quite limited AFAIK. 2A3's also, though not quite as limited, though the simple Sovtek 2A3's are actually excellent tubes in my amps, and well respected. NOS 2A3's go for some pretty large coin too, though not quite as much as the 300B's that were mentioned, which I think is ridiculous personally.
Marco
As far as the overpriced WE 300B tubes, do keep in mind that they are by no means the only good choice. There are plenty of decent 300B's out there that you don't need to sign over your first born to obtain. Certainly the WE's are an outstanding tube, and I use a pair myself, but the more recent production tubes typically can be found for $400-800 pair and have a predicted lifespan of 10,000 hours. I've read a few recent shootouts and comments here that maintain that the newer Svet's and the JJ gold's are not far off the mark, and to some ears may be superior than the WE's. There's an abundance of 300B's to choose from in current production. Your selection of current production 845 tubes is quite limited AFAIK. 2A3's also, though not quite as limited, though the simple Sovtek 2A3's are actually excellent tubes in my amps, and well respected. NOS 2A3's go for some pretty large coin too, though not quite as much as the 300B's that were mentioned, which I think is ridiculous personally.
Marco