Is it a OK to leave tube pre-amps powede up 24/7

@czarivey 

1. tubes dissipate heat that dries out electrolytic caps.
2. occasionally blown tube can blow other circuit components or even set circuit board on fire.

1. So do transistors
2. I've owned tube equipment for 25 years and have never had a tube "blow."  I've never even seen one on TV.  And should a tube go into thermal or current runaway, there are fuses or sacrificial resistors to shut off the juice, at least in modern and properly designed units (in which category both of the OP's components fall).

Any component can fail, and I'm sure there are cases of spectacular failure.  But that goes for both tube and solid state and is the exception.  Cars can catch on fire too.  Most don't.

 

The tubed ARC pre should be fine left on while you are out of the house, but ARC power amps definitely and absolutely not. Their power tubes aren't fused, and when one pops the amps have been known to burst into flames. As I am most likely about to be ;-).

1. transistors in most class A/B and class D amps don't and there are many class A/B amps that don't run hot.
2. I've repaired tube equipment with burned circuit board around blown tube more than once and for me one is too many anyways.

Old saying says -- No problem till the SHTF. Right?

and says the power surge upon turn-on is harder on the tubes than 24/7 usage.

This really has to do with the design! The phenomena known as 'cathode stripping' really affects power tubes a whole lot more than small signal tubes!

I find that I get much longer life out of the tubes if they are only on when I'm using them. After 20-30 minutes they sound great and after about 2 hours they've gotten as far as they are going to go. Running a tube preamp 24/7 is going to shorten the effective tube life unless you work at home and have the stereo playing all the time.

Or are retired!