I've had my set for around 9 years, and it's one of my best electronics purchases ever, I worship these speakers! I'm about to go by a new set because the jack on the back of the sub was damaged by accident, screwed everything up. I'm not even interested in any other manufacturers, these are the bomb. Regarding powering them off, I turn mine off with the power switch on the back of the sub every night. The sub gets pretty darn warm being on all day, so that's why I turn it off.