leave power on?

If your equipment is well designed then turning off and on is absolutely no problem.

Save energy.

As I've said so many times before, this leaving stuff on all the time is simply unsubstantiated lore and in fact caps benefit from being charge cycled.

In almost 40 years of audio as a hobby, I have never had a piece go down or degrade due to turn on turn off cycling.

I turn off my Int amp if im gone from the room more than 30-45 min. Having had 2 tubes arc i do not want to leave it one and leave the house.

I have a Tube Box Se and i leave it on all day if i'm listening vinyl off and on but turn it off for any long absence.

Most of the SS gear I've owned sounded better when left on 24/7. Most tube gear sounds best after a warmup of between 30min and 3 hours. Otherwise leaving tube gear on always is a waste of tube life IMHO.