Specialty tube dealers like Andy Bauwman know all the test and matching parameters for popular audio products. Not only can he supply perfectly matched sets, but can suggest some NOS brands to push your system performance in the direction you want.
OEM tubes supplied by manufacturers are the same Soviet and Chinese stocks available from a dozen sources. They may be select and matched, but for what they charge there are usually better alternatives.
OEM tubes supplied by manufacturers are the same Soviet and Chinese stocks available from a dozen sources. They may be select and matched, but for what they charge there are usually better alternatives.