Nos Mullards or telefunkens will last as long as you own your equipment. I’ve got some from the 50s and 60s that still test 90%. They must have at least 20 k hours on them. Obviously mine are not nos but I’d feel real comfortable paying good mo eye for them from Brent Jesse or another reputable tube seller.
How long should Pre amp (12au7) tubes last in Rogue Preamp?
I've always heard Rogue equipment drives tubes hard. My RP-5 (purchased in OCT 2017) still sounds great with the stock JJ's. No distortion or any added noise. Typical life (in hours) of general 12au7's for a Rogue preamp? I may try the newer Gold Lions next time, although I am happy with the sound of the JJ's