You have to look at that in terms of SD A single 12 is .05 sq M of SD, so .1 for the air A single 15 is .08 sq M of SD Then you have to factor in xmax (this is for general displacement purposes) The pair of 12s is 2.4 and the Single 15 is 1.92 Now, the question lies in are the 12s reaching Xmax off of 600 per driver? The 15 assuredly is reaching it off of 1200 watts. The 15 could very possibly be throwing farther than the 12. And the gap is closed somewhat. I'm sure the two would be very close in terms of output. I would like to say the 12s would inch out ahead, since that is what I am going to be using . EDIT - Both in their respective recommended ported applications.