To leave on or not to leave on, that is the ?

Dear members,

I tend to leave on, all the time, my CDP/transport and dac (Wadia 23 and Audiomeca Enkianthus). An audio engineer friend has just adviced me that he believes it shortens the life of the gear (I had heard this before about DAT recorders and do keep mine off until it is used). He thinks warming it up before critical listening is good but not to keep them on constantly.

I do turn all equipment off when the fear of thunderstorms or ice storms is present but generally all my equipment, including the SDS controller for my VPI, stays on always.

I am really screwing up something? Advice, as always, is greatly appreciated.