Do you always keep the Amplifier powered on

On my solid state stuff, I keep the amp AND tuner on and playing 24hrs a day. Sometimes for months.

"I do not know exactly what electricity costs". I guess that was a understatement.

Without regards to sound quality, safety, tube life, and general wear and tear (none of which I claim to be an authority on), these days you can't ignore the fact that leaving everything on wastes electricity.

That's true it wastes electricity but so does making coffee, watching TV etc. It is for me a matter of convenience. With high power class A amp it might be a different story.

If you are making coffee on an aircraft carrier two hundred gallons at a time could be, my 5 minutes for 2 cups not so much.