I have trolled through a number of threads but could not find an answer to this question : Regarding a Valve Audio Exclame 150, when not in use for some time (let's say two weeks plus) is it better to switch the unit off at the mains or is it better to leave it plugged in and in standby? At the moment it is left on in standby. However as I walk past the amp at night I see a faint glow from the valve and I wonder whether I am unnecessarily reducing the lifespan of the valve.