Hey you forgot nose ring and tatoos! Yeah you are going to need a PA, it's about the only way to balance out the sound of a band and have any kind of dynamics in your sound, you also want to be able to spread the sound out as evenly as possible, when you start cramming people in a room it's not real good for the accoustics of the room, what may sound loud onstage might be inaudible at the back of the room.....