I dissagree with abstract7. a typical 8 ohm or 4 ohm speaker has nothing to do with the loudness of the speaker. Only two things affect the loudness of a speaker. 1. Efficiency, (how loud the speaker will be with a given power input.) 2. power input. It is true that most amps will put out far more power into a 4 ohm load than with an 8 ohm load. however, almost all speaker's sensitivity rating are at one watt at one meter and one watt is one watt, regardless of the speaker load on the amp. So, a speaker with a sensitivity of 90 db would play at 90 db at one watt weather it was a 16 ohm speaker or a one ohm speaker. That's a scientific fact. I think what abstract7 was getting at was the fact that a 4 ohm speaker will increase a typical amps output by an average of 70, 80 and in rare cases, 100%. It's that extra power output that makes the speaker louder, not the ohms.
