I have finally decided......

Rwd, tube life will be shorter if you leave tubes 24/7.
tube life will also be shorter if you won't wait and operate them before they rich steady state. 10...15min for small signal tubes and 30min and upto 1hour for power tubes.

If you're leaving your tube components on while you leave home for work and one of the tubes is blowing($hit happens) usually it is a great idea to turn it off immediately. Supplying a dead tube with DC can damage the other tubes. A lot of manufacturers do suggest it and I had multiple technical conversations about tube circuit topology and the reasons why they suggest to keep the tube equipment off especially if it's unatended. It's certainly more critical for power amps than to the phono or preamps but still the potential possibility stil exists.

I happened to be also the owner of PH3 and while i clean a group of records that i want to listen I turn it on and wait 40min since I have tube power amps as well. For ph3 15min is sufficient enough. The life of 6922 is 10000 hours among which only 7500 hours have no impact on sonic performance. I roll these tubes after they rich that period of time. If you will keep them 24/7, you will end-up using them a-little bellow a year. I turn my tube equipment completely off when I go to bed. I have daily listening sessions usually from 7pm to sometimes mid-night in week-days and i might keep the tube equipment on the whole day during the weekend if I'm home otherwise whether I go to work or go to bed i turn it off. With right electronics there will be nothing from turning it on or off. The main killer to the tube is passing the input signal when it's not in steady state.

Russ....your last statement scared me to death!! But I think I'll live with them "on".

Marak....do you mean "tube life will be much shorter" turning then equipment on-off?? or just leaving them ....on?? Sorry, I didn't understand.

FWIW, that's what I do, unless I'm out of town or know I won't be using the system for a while. And my equipment, Jadis, is much more "on the edge" than ARC, in terms of whether anything can go wrong. I am trying to convince myself that the turn on/turn off cycling of the tubes wears them out faster than leaving them on all the time, but I think that argument is the same as leaving your car running all the time instead of turning it off and starting it up when you use it because you use more gas starting the car than when it's idling! Nothing has gone wrong yet, but my fear with this practice is that something might go wrong enough to cause an electrical fire while I'm not there; don't know if that's reasonable or not. Any more informed opinions?

there are two points there which you will have to choose:

1. tube life will be much shorter and i wouldn't recommend to do it with expencive NOS tubes. it wouldn't heart small signal tubes to be switched off for the night and than after you come home run to heat-up for just 10min.

2. you will have some benefits on running them on since one hour worm-up time is more beneficial to the sonic performance than 10 min yet id depends on the tubes and its age as well.

and finally less-likely your electricity bill will grow from small signal tubes.