I have a Sim Audio W5/P3. It is about one year old and has never been off except during bad electrical storms. I have not read the manuel lately but I'm pretty sure the manufacturer even reccommends leaving it on. You could check with your manufacturer to see what they reccommend for your equipment but I always leave mine on.
Solid state power amps.; on or off?
Some people keep telling me that solid state gear should be left powered on all the time during day to day listening. They claim that thermal consistency will improve long term life and reliability. Power cost consideration appart, what is your opinion; experience?