Ok.. i've been talking to my friend, who is a professional speakerdesigner, and he gave me a whole filosophy about cabs.. the bottom line was something like this : lets assume that all cabs are : 2x10 = 300w / 8 ohm 4x10 = 300w / 8 ohm 2x12 = 300w / 8 ohm 1x15 = 300w / 8 ohm he said that 4x10 + 1x15 = muddy lows and slight increase in volume. 4x10 + 4x10 = increase in volume, but no change in sound. 4x10 + 2x10 = increase in volume, and enhances the sound.. better lows and tighter mids. 4x10 + 2x12 = same effect as 4x10 + 2x10, but with slightly better lows. af first i was thinking of getting a 4x10 + 1x15, but his theory on the 1x15 makes a lot of sense to me.. he said that a 2x12 has a lot more speaker surface and could therefore create more volume. and because 15" speakers are relatively slow, the 2x12" would have far better mids and lows.. also he said that making ports or vents for 12" speakers is easier.. this is ofcourse all asuming the wattages, ohms and housings are equal. i would love to hear your opinion on it..