[thxgoon]

Well if you had a way of measuring you would send exactly 2.45V of white noise into your speaker and measure with a calibrated mic from 1m away and that would tell you your sensitivity for a 6ohm speaker. You could probably achieve this using a digital multimeter and slowly turn up the volume until it reads 2.45 volts though I may be wrong considering this is an AC system so Ohm's laws doesn't apply exactly???