Stay inside. Disconnect the speaker wire at your AVR and test the resistance of each speaker and wire (meter hooked up to + and -) with an Ohm meter or multi-meter. Cheap multi-meters are $10 and nicer ones are $25 at Sears and probably at Radio Shack. At rat shack you can probably get the sales girl to show you how to use it.
Man Card Demerit: 3 points