The Chinese 845 is really a good tube. I would not be afraid to buy it and run it in your Bel Canto.
If you want better, you must buy NOS American or British tubes such as Cetron, RCA, GEC and GE. The least expensive of all of these will be more than $300.00 each as new old stock. The most precious will be in excess of $500.00.
I personally would not even consider putting that kind of money into a single tube. If you want extra performance, the Chinese tube cryogenically treated will perform 75% or 80% of maximum possible in your amp, and for a fraction of the expense.
If you want better, you must buy NOS American or British tubes such as Cetron, RCA, GEC and GE. The least expensive of all of these will be more than $300.00 each as new old stock. The most precious will be in excess of $500.00.
I personally would not even consider putting that kind of money into a single tube. If you want extra performance, the Chinese tube cryogenically treated will perform 75% or 80% of maximum possible in your amp, and for a fraction of the expense.