Do I NEVER shut it off…?

Whether a bad practice or not, i never leave something on forever. Heating and cooling cycles may cause strain but depends also on on construction and casing and how fast it cools down after shut off.

As I was told by a man with a great ear who owns several amps
including a Pass 250.8. Off, then a  One hour warmup. 

As I was told by another very experienced fellow also with a 
great ear. Keep the DACs on always. SS may take a week to 
fully wake up.

I go with the One hour warmup. Even for the DAC. After all there
must be some advantages to a limited hearing range.

As I was told by another very experienced fellow also with a
great ear. Keep the DACs on always. SS may take a week to
fully wake up.

I don't know about the ears but this one is a great listener. The other one, not so much.

I had the same question for whether to keep my first watt j2 on all the time or no. i posed the same question to Nelson Pass and he said one should keep it off until an hour or so before listening. Keeping it on all the time can reduce its life he said. 

You can leave it on all the time but it is best to shut it off for obvious reasons but for the best sound all the time you need to leave it on.