The original WE300B's last a VERY long time in amps designed to run that particular tube. I would check to make sure the LM amp is not running the tube hot like many current amps do to extract that little bit of extra power. I agree that original, engraved base 300B's are very good tubes. I think they run a bit more than $6,000 a pair for used tubes that still test strong. The 300A's are now more than $15,000 a pair. A local dealer uses engraved base 300B's in several amps that he builds and sells (in mostly pushpull amps, so this means quads of these tubes), and is currently looking for a couple of 300A's to complete a quad for a very special customer.
I would look at the new Western Electric 300B's coming on the market that are being built using the old machinery and tooling from Western Electric. These are probably going to be like the 1990's Western Electric tubes--decent, if not quite as good as the originals. I have not listened to Taketsuke 300B's from Japan, but, they are reported to be good replicas of original 300B's. I heard, and liked, the Kron version of 300B's, but, they are different in sound from typical 300B's so some may not like them (leaner, more dynamic sounding than typical 300B's).
If these seems really crazy, it is, but not as crazy as a tube that is similar to the 300A or 300B, which is the Western Electric 252. This same dealer has a 59B amp that runs those tubes in pushpull. The tubes really don't have a price on them because there is no market for them, but, he turned down an offer of $30,000 for the pair.
I would look at the new Western Electric 300B's coming on the market that are being built using the old machinery and tooling from Western Electric. These are probably going to be like the 1990's Western Electric tubes--decent, if not quite as good as the originals. I have not listened to Taketsuke 300B's from Japan, but, they are reported to be good replicas of original 300B's. I heard, and liked, the Kron version of 300B's, but, they are different in sound from typical 300B's so some may not like them (leaner, more dynamic sounding than typical 300B's).
If these seems really crazy, it is, but not as crazy as a tube that is similar to the 300A or 300B, which is the Western Electric 252. This same dealer has a 59B amp that runs those tubes in pushpull. The tubes really don't have a price on them because there is no market for them, but, he turned down an offer of $30,000 for the pair.