solid state gear- leave on?

It'd neither a good idea nor a bad idea. An amp will sound its best when warmed up and ready to go and every second thereafter will not improve things one bit. If the amp requires many hours before being warmed up, then, yes, I'd go for 24/7. If it only takes 20 minutes, what's the point?

There's no problem with leaving the amp on all the time. There's also no problem with turning it on and off as needed. Whether one way or the other results in a shorter life span has, to my knowlege, never been proven. Who knows - the "stress" effect of cycling and the thermal effects of 24/7 operation may be a wash.

If you leave the amp powered on all the time you have to guard against surges. Being away with a thunderstorm in progress and an amp powered on at home is very trying to say the least.

I agree with Gs5556 on all points. I might add that I think that on/off cycles may affect tube gear, but not SS. It's no coincidence that light bulbs typically burn out just when they're turned on, not when they've already been on for a while. I would expect tube filaments to behave similarly for the most part. It might be good to check with the manufacturer of your component. My favourite manufacturer states that leaving its gear on all the time causes no harm other than using electricity. However, they also advise that if you're not around for any length of time, you should not just turn it off, but also unplug the mains. A lightning bolt that can arc a mile through the air isn't going to have any trouble with the gap at an on/off switch. I've personally had a surge suppresor die in the line of duty protecting my gear from a power surge during an electrical storm. Now when I hear thunder, everything gets unplugged.

I also must disagree with Pabelson's take on a couple of points:

"Tubes take a long time to settle in, so keeping them on makes some sense; for SS, just turn it on a few minutes before you start listening."

A) Tube gear requires less, not more, warm up time than solid-state to sound its best. The fact that tubes need a minute at the start and transistors don't is a red herring that I believe you're confusing with the more important aspect of how a piece of gear will sound over, say, a typical 2 hour listening session if started from cold. Tubes will be most of the way to their best after 15-20 minutes, but transistors will need at least that whole 2 hours, and preferably a whole day to really come into their own. Saying that you can flick on SS gear a couple of minutes before you listen and hear everything you paid for is naive, although if the piece of gear in question has a semi-powered standby state the difference may not be nearly as great.

B) In most cases it makes much less sense from a practical standpoint to leave tube gear always-on - you'll wear out your tubes several times quicker. And if we're comparing class-A/B power amps, then regarding energy usage ethics, the tube gear will draw much more power at idle than the SS.

Well said Zaikes....Pabel's advice was the opposite I've learned and heard over the years...my NOS tubes aren't cheap and I leave my SS power amp always on and the tube pre and cdp I ignite about 1 hour before listening and turn off when I'm done.

My experience leads me to believe that leaving my SS gear on all the time is crucial for best performance. Anecdotal evidence: coming back from a 4 day weekend w/ my gear powered off, it took at least 4 days to sound good again. That convinced me to leave them on 24/7.

However, in the February "Stereophile" review of my amp, the reviewer stated that the amp sounded good after 20 - 30 minutes and didn't improve after that. Oh well.

Also, longevity doesn't seem to be an issue for SS gear w/ literally thousands of on/off cycles. My old Hafler and NAD SS gear were always turned on and off. They're both still going strong at 25 years and counting.