I used to have a preamp that was tube rectified (6X5) with a pair of either 6SN7 or 12SN7 (switchable) tubes for output.
I always purchased NOS matched pairs from Brent Jessee.
Some were used sparingly while some were used for longer periods of time.
For example, one pair I hardly used is a nice pair of "Chrome Domes"(?):
Total pairs: three 6SN7, two 12SN7, 12SX7, 6SL7; and two individual 6X5.
Anyway, I'd like to discuss off-line with someone about what to do with these.
