I must second Imin2U's last comment about keeping hi-fi gear powered up.
The proprietor of one of the high end's more noteworthy and successful tube gear companies explained to me that the studies done in the 1950's on tube wear all confirmed that small signal tubes such as those used in preamps and DAC's last much longer (and as a corollary, also sound better) if powered up 24/7. Basically, he said that, if left powered up 24/7, they either die at some point in the first 250 hours (infant mortality of sorts) or they basically last forever.
I leave all of my equipment except turntable and tube amps powered up 24/7. Over the years, this has included a tubed DAC (Cal Audio) and three tube preamps (Jadis, CAT and Hovland). In fourteen years combined of these tube components being left on 24/7, I have never had to replace a tube (nine years now on the DAC), nor has any of my equipment, tube or solid-state, required service. As for the preamps, when I am not listening to them, I am careful to keep the volume turned all the way down and the mute engaged.
Tube amps cannot be left powered up because the output tubes pass a relatively large amount of current that stresses the tubes, and do last longer if turned on and off.
As a general rule, however, I believe that Imin2u is correct -- it is the thermal cycles that occur when equipment is powered up and down (i.e., repeated expansion and contraction of the components as they heat up and cool down) that kills components, even tubes - it is basic physics.
The proprietor of one of the high end's more noteworthy and successful tube gear companies explained to me that the studies done in the 1950's on tube wear all confirmed that small signal tubes such as those used in preamps and DAC's last much longer (and as a corollary, also sound better) if powered up 24/7. Basically, he said that, if left powered up 24/7, they either die at some point in the first 250 hours (infant mortality of sorts) or they basically last forever.
I leave all of my equipment except turntable and tube amps powered up 24/7. Over the years, this has included a tubed DAC (Cal Audio) and three tube preamps (Jadis, CAT and Hovland). In fourteen years combined of these tube components being left on 24/7, I have never had to replace a tube (nine years now on the DAC), nor has any of my equipment, tube or solid-state, required service. As for the preamps, when I am not listening to them, I am careful to keep the volume turned all the way down and the mute engaged.
Tube amps cannot be left powered up because the output tubes pass a relatively large amount of current that stresses the tubes, and do last longer if turned on and off.
As a general rule, however, I believe that Imin2u is correct -- it is the thermal cycles that occur when equipment is powered up and down (i.e., repeated expansion and contraction of the components as they heat up and cool down) that kills components, even tubes - it is basic physics.