Peter Elem wrote:

AS with $5 vacuum tubes, $150 audio vacuum tubes sometimes fail at an early
age.........One culls them out and often very old tubes just keep on going
fine. 12AX7's have become "fools gold" in this inflated acoustic
psycho-babble golden ear but tin brain market...........

Amen to that ! They were the 2N2222/2N3904 or BC108/BC184 of their day.

Graham