You probably will get that many hours out of the output tubes depending on how often and hard you are running the amp. For many listening a few hours an evening and a few more on the weekends that is years of use. It's very easy to replace the output tubes and not that great a cost--just pull a tube out and pop in a replacement.

Hey Mark, I think Lon pointed in this direction... but I will elaborate from my experience. I run my amps a lot... often 6-8 hours or more in a day, but they are off otherwise. Also as Lon suggested, harder play can wear more on the tubes... so variabilities...

But at an average of 6 hours a day, the math is way different that 24/7 as you calculated it... 6000 being about three years. And as Lon said, many more if a person listens less per day and turns the amp off between sessions... Left on 24/7 with tube gear is something I have heard of, but rarely.

Actually the 6P15P-EV or ER tubes that we ship in those amps are rated at 10,000 hours and the majority easily reach it in this amplifier.

The problem is in reality that they last too long. What happens is a customer buys the amp and does not purchase a spare tube compliment. Instead he looks at the tubes like part of the amplifier which they are no more than a light bulb is part of the light socket. So they run the amplifier until a tube nearly fails or completely fails. As tubes wear they become smoother and more rolled. Well this tube has bandwidth that is many times that of an normal audio tube, so you don't hear it roll off, but it does get weaker, softer and smoother like any other tube when it wears down. This process takes so long it is not noticed. Which in fact means that in most cases years went buy listening to the amplifier with compromised tubes and subsequent fidelity.

We recommend a spare tube compliment and tell our customers to own a spare tube compliment for the amp made up of new tubes. Every 6 months put the new tubes in the amp and see if you hear a big change. If not, but them back in the box, reinstall the old tubes and enjoy the music. This will keep you from accidentally listening to worn soft over used tubes. Or, in the case of the first 6 months or so, make sure all of the tubes are healthy without any defects that are effecting the sound.

We tested a set of tubes in a zen amp by installing them into the amp and leaving it on until we noticed a problem. It went 24 hours a day for 7 years as the shop radio that was never turned off before a tube failed. So that would have been 61320 hours.  It would have sounded less than it's full potential for 51320 hours before it finally failed.

- Steve