StaeI've read that 10,000 hours is a good rule of thumb for these tubes, so we're talking a good 10 years of listening at 5 hours a day, 5 days a week. But then people have mentioned that the amount of power that is put through the tube in the T1 is minuscule compared to what goes through them when they're used in a full-size amp, so I'm guessing the tube could last a lot longer than that. Does anyone more experienced have input?