Leave it on?

And thanks guys for using this an opportunity to lecture us on climate change.  Again lets talk about nuclear and not the other other underperforming solutions.

You're so very welcome. And you sound a bit touchy about the topic. I heard a couple mentions but no "lecture." Why not nuclear AND renewables? It works in many places not stuck in binary ruts. Read up and try to think a little bit.

Keep my solid state equipment on 24/7.

Audia Flight phono, SMc Audio, Merrill Audio, Martin Logan subs

but no "lecture."

yes exactly. There is a history of how the deniers refused to be lectured. And perhaps the believers sometimes talked down to them and triggered the refusal to be lectured.

We are in the same boat. Facts are not up for discussion, we are all subject to gravity and boiling in extreme heat.

I turn my gear off when not in use, and I have never had a tube go bad even after 15 years of regular use.  Of course, I cannot say that I would have had a shorter life for my tubes if I left them on all of the time; I have no comparative data.  There are many ways for a tube to fail, but eventually all tubes will exhibit lower emission of electrons from the cathode due to aging; turning off gear when not in use reduces this kind of tube degradation.  If an amp is designed correctly, the early failure from the effects of being turned off and on (e.g., thermal shock) should be reduced enough that it makes more sense to turn off the amp when not in use.  As for other components, heat can degrade some components and this will favor turning equipment off to reduce exposure to heat, but, some capacitors might fair better without being turned off if they are susceptible to damage from high inrush current.

The vast majority of tube gear manufacturers will recommend turning off gear when not in use.  The downside mentioned by those who don't recommend turning off their gear is usually not so much shortening tube life as it is performance is affected until the gear warms up.  The gear I am familiar with usually sounds decent after five minutes or so of use, but, I am aware of some gear that takes much longer than that to warm up (supposedly an issue with the capacitors taking some time to fully reform and stabilize).

I would go by whatever the manufacturer recommends. Generally, I leave most of my gear "on" or in "standby".  If I owned a Class A solid state or tube amp, I'd likely turn it off in the summer to keep from heating up the room too much but might leave them on in the winter. As noted, thermal cycling is what kills electronics or them getting too hot from the buildup of dust - so every once in a blue moon, clean your gear out carefully - or cover up the ventilation holes and slots when not in use if they are turned off. Streamers, your Wi-Fi router, and modem need to be rebooted every once in a while, to maintain a good connection and clear out any "cobwebs".  I do mine about once a month.