Do you always keep the Amplifier powered on

I turn everything off when I am not there.
Used to be a volunteer fireman, you see how easy a house can burn.

I'll share Schubert's POV.
It's only 15...20 for solid state to reach operating parameters and half-way down for tubes. Becides, if area is prone to surges, you're saving your equipment when not home.

I do not know exactly what electricity costs. But if it runs 1.00 a day to have an amp on all the time it adds up to about two hundred and fifty dollars a year you save if you only turn it on 6 hours a day. And that adds up to two thousand dollars in ten years which should be enough to have some caps and a power switch replaced. I think these figures might be quite conservative for an class a, ab, or a tube amp. And you will also be making a better world for the cute mice that live in the fields. Sounds like a win win win proposition.

A dealer I trust said it takes 24 hours for solid-state to reach its peak (1-2 hours for tubes).
If you listen every day I'd leave it on (not class-A however). If you listen only on weekends, turn it on Friday morning for Sat-Sun (connected to surge control of course).

Electricity in my area costs about $0.006 per kWh. For 40W it would be $0.0576 daily = $21 per year. My amplifier (total idle power = 10W) that costs me $5/year doesn't even have power switch. No power switch on my Benchmark DAC1 (also 10W) or Apple express as well. All is plugged into Furman power conditioner, including DVR set to record shows. Unplugging all three individually doesn't appeal to me. Furman has strong non-sacrificial under/overvoltage protection but I still unplug it during thunderstorms.