Originally posted by U2Nick:[..]
If you use a tube amp "regularly," how often would the valves need to be replaced?
"Regular" being something like...
1/4 - 1/2 volume three days a week for about two hours each day, with one day of 3/4 to full power for four hours.
I honestly don't have experience with velves, but I hear that they usually last about 5 years in moderate use. I have heard about some bass amps that have valves that are 40+ years old, but they were probably not used to get distortion, so they were not pushed to the limit.
I don't think that it will be an issue. The distortion from valves is much better than the distorion from transistors. The only bad thing that I see about valve amps is that they are heavy.