I leave mine on all the time, even the amp with Nuvistors. But I wouldn't leave a Class A amp on. My line stage has a standby as it has a Class A circut. I also have protection in case of storms when I am not here.
Do you leave your components on 24/7?
Lately I've been leaving my components on all the time, on the assumption that a) they'll be ready when I want to listen, and b) the on/off cycle ages the equipment (tubes, anyway) faster than leaving everything on. Is the latter a reasonable assumption?