There must be an optimal answer to this question of leaving tubes on or off but I have never been confident I have found it. In the hay day of tubes the largest numbers were used for digital applications which are less sensitive to noise than are analog applications. Thus, the data with the greatest statistics is not totally relevant.
After listening to lots of experiences opinions, I have come to believe (without really any definitive evidence other than dealers', audio engineers and serious audiophiles I have talked to) that it is best to turn amps on only once per day and turn them off before going to bed. And my most trusted, experienced source would say, when in doubt keep them on because it is the on and off cycle that makes the tubes go noisey.
Sorry, but this is the best I can do. I just know of no controlled test with data to really answer your question. But there are lots of opinions.
After listening to lots of experiences opinions, I have come to believe (without really any definitive evidence other than dealers', audio engineers and serious audiophiles I have talked to) that it is best to turn amps on only once per day and turn them off before going to bed. And my most trusted, experienced source would say, when in doubt keep them on because it is the on and off cycle that makes the tubes go noisey.
Sorry, but this is the best I can do. I just know of no controlled test with data to really answer your question. But there are lots of opinions.