Do I NEVER shut it off…?

Leaving it on 24/7 is ridiculous!  Absolutely no science behind any of it!  Just peoples theories.    Turn on, wait 30 minutes to an hour to get warm, then enjoy.  Been doing this for over 25 years with some of the finest amps in the world.   Works perfect!  Pretty common sense here,  come on!

My SS equipment stays on all the time.

No need to leave amps on all the time, just turn them on for awhile before you are going to listen so they can warm up. How long that is you'll have to find out or take the advice of other owners.

I  have a pair of Class A amps that use up 300 W each when not putting out any sound. Keeping them on all the time would make the electric meter spin like a kid's pinwheel toy and would also turn any room they were into into a sauna in summer.

Like I said, it depends on the amp. Not a black and white issue people (as few are...).

I have all Ayre electronics which provide a trickle charge when "off". I don't hear a change from when I turn it "on" to an hour later, however, MCarbon may very well be right.....so I'll leave it on for a couple of weeks, turn it off and listen again the next day.  Thanks for the tip.