Tube replacement schedule?

[Accio Recto]

Is there a recommended schedule for replacing tubes in a Dual Rectifier? I have a 2-channel from 2000 with the original tubes still in it. From what I can hear it still sounds great, there's never been an issue with the tone. (I never drive it all that hard.) Does anyone think there might be a benefit to replacing the power or preamp tubes?

I'm just kind of concerned that the original tubes have been in there quite a while. What kind of luck have you guys had with tube life?

 

[ToneAddictJon]

If it sounds good, theres no reason to replace them. The only time I replace tubes is when things don't sound right, or if I want a subtle variation. There's no time limit set on tubes, different or newer tubes will just bring a variety of tonal differences, some better some worse, so if you like your tone, don't mess with them 'til it stops sounding good, things to watch for with tube failure would be the power tubes, if you turn off the lights and you can barely see them glowing, that would be when to replace them.