My contribution to the thread:
Power amps (Solid State) and cd player are always on because you can't swich them off unless you plug them off, they are build to be in stand by all the time, a part when you listen to them!
All other stuff, preamp (tube), phono preamp (SS), power conditoner and TT are switched off when I don't listen to them.
The best sound comes after an hour of listening/warming.
When I left home for a weekend or more I disconnet everything from the socket.
I use to play some demagnetizing tracks (on cd and record) when I plug the system in.
A part holy lightning and curse, I switch the system off because I don't want to contribute at the global warming for audiophile reasons.