Generally not. Just make sure you get the full manufacturer's warranty. I wouldn't buy a demo from a large warehouse store where people may have walked in and cranked it up louder than is reasonable. But otherwise you'll be fine. There are even some advantages. The speakers will be broken in so you'll have a better idea of what they really sound like. Electronics are very reliable, but if they're going to fail it's likely infant mortality. So you'll be past that stage.