Turn off or leave on?

My experience - I could leave my solid state amps on, or on standby, with no problems (like the Krell FPB600) over several years of use. My Atma-sphere MA1 tube amps are another matter - I turn them off, after use, to preserve tube life. My Io phono preamp, also using a lot of tubes, is another matter. I fell in love with how good the Io sounds, fully warmed up, so I left it on, all the time. Not a good idea. Not just because it took tube life, but also because some components - including crackelating soldering - did not like it. Also, I used to have my Einstein The tube preamp on, most of the time, and when I sent it to service, recently, several components (capacitors, mainly) had to be replaced.

A main rule becomes clear. Regardless of the cost in tube life. How components react to "always on" depends on time x heat. With more heat, e g restricted air flow above the component, the problems increase over time, the longer you leave it on.

TURN OFF!!!  We're killing the planet enough already... you can wait a stupid 30mins to reach your audio nirvana for the sake of our future.... which of course is screwed no matter what we do now...... but still.....  

Regarding turning off devices to save energy… Just be aware, as long as you are hitting your house, you may as well leave these things on. All they are doing is contributing to the heat in the home, and so you are using your furnace less. This is even true for lightbulbs. The only difference is if you have a heat pump system, which is more efficient than other sources of heat.

All solid state gear should be left ON all the time. That's their happy zone.

My domestic keeper has tried over and over to find enough excess electricity usage to make the case against power-on but has failed miserably.

My Aesthetix gear specifically instructs to turn off when not in use--i presume to preserve tube life. I'm curious whether other manufacturers give instructions on this as well ?  If they don't i would contact them and ask them.