Assuming each example has max recommended airspace and max power, what would make more of a difference in SPL? More cone area, more drivers, or more power?
Say you have 2 SA-12s getting 1500 total, vs 1 SA-18 getting 750. Or maybe 3 SA-10s each getting 750 vs 2 SA-12s each getting 750? Or 1 SA-12 getting 750 vs 2 SA-12s only getting 325 a piece? Or one SA-12 on 750 vs one higher level 12 on its respective max power? Or one SA-12 on 750 vs one SA-18 on 325?
My theory is that 2 SA-12s have less cone area than one SA-18, but the 2 12s have a combined total of 38mm of xmax, where the one sa-18 only has 19mm. So I think that the 2 SA-12s would be louder.