Certain vintage tubes have a tough time in phono stages or in high gain line
stages because of microphonics and/or other noise. You have to consider the
gain of the position you're putting the tube in, plus the net downstream gain.
Some tube sellers have various grading scales which indicate where the tube can
be appropriately used -- e.g. Upscale Audio's Platinum Grade tubes are good for
phono stages, whereas a Driver Grade tube will be too noisy in that application.
Some sellers don't test/rate for noise/micro, which makes it a gamble. In my
experience, the older 6SN7, 12BH7, and tall-plate 12AX7 tend to be problematic
in high gain positions. So you don't really have a complaint against the seller
here unless it was advertised as a super low noise/micro tube.
Some people report that tube dampers and/or component footers help a bit.
