VAC recommends leaving their Signature-type preamps on 24/7 unless you're going to be away from the system for an extended period. That's what they do. I was told to expect to change tubes every 5 years using this regimen. Clearly, they expect a lot of tube life in their circuit. YMMV.
Tube Life
I’m using a phono pre-amp with a pair of telefunken 12AX7 and one 12AT7. I purchased these tubes several years ago and they were rated at about 50% life. Are tube noise and tube rush the only reasons to change out tubes? Everything is silent and yet I can’t help but think that several years of use should indicate some sort of wear. Any experience or suggestions will be appreciated.