Audio Research PH3 Owners

I have a PH3SE which I leave on 24/7. I'm curious if other PH3 owners are doing the same. If so, why. If not, why. Also how long can I expect the tubes to last. Thanks.
I have had my ARC PH3 for 2 years and have yet to replace
the tubes. I only turn it on about an hour before I plan
to play music and turn it off afterwards. This I do to
keep from burning out the tubes prematurely. I too would
be interested to hear from the experiences of others.
Turning on and off the equipment is more harsh on the tubes than leaving them on. Leave them on if you listen quite often. If you plan on not listening for more than a few days, then turning the unit off. If you leave your unit on 24/7, the tubes should be replaced 2-3 years. Occassional listeners like Kinsekd could probably expect his tubes to last longer. The best thing is to always have a spare pair available. Try compare the old set of tubes to the new set and see if there's any sonic differences. If it is pretty obvious, then that means the old ones should be replaced. If you use NOS tubes, it is better to stock up some now, as I've seen prices drastically going upward for them.