I hate to leave any piece of electronics on for an extended period - especially if I'm gone - I have a McIntosh MC-2100 amp and it gets fairly hot(enough that you can only touch the hot spot for a few seconds) - it doesn't have a power switch, so I plug it in to a power strip and shut it down every day - I don't think it makes a difference in the sound that much - but heck, I'm over 50, so take everything I say with a grain of salt.
