How do I know when too much volume is bad?

[alkalinesi]

Hey guys, this is gonna sound like a newbie question, and I apologize. In my movie room(see sig for equipment) I always keep my Pioneer receiver volume around -10 db and thats pretty loud for my small room. But I never really took it up to like the positive volume range (like +10 db) out of the fear for blowing my speakers. So with audio I'm a newbie, so please shine a little light on the question, with my equipment, how high can I crank it before it starts to hurt the speakers? If some of yous have similar setups, where do you keep your volume at? Thanks in advance guys.