If the switch is mechanical there is a way to wire it to be always on. Just do that, and just leave it on.

I know you can't do that with tubes or class A stuff, but a regular class AB amp will be fine. And usually it will sound better and better as it burns in. Just leave it on forever. I do with mine, and I do not see a huge electric bill or anything. They might pull about three clock radios worth of power, which is about nothing. I mean like a dollar a month if that.