More cone area in a single 15 than three 8's, and the 15 has more excursion than an 8 as well. That's why I used the term "displacement". An SA15 has 48% more displacement when you consider cone area and excursion. Again, this is assuming you're running all of them at full stroke. The SA8's would have significantly more motor force and would be more efficient, as well as 50% more power. In theory, the power and efficiency make up for the displacement differences, making things nearly equal. Oh wait, that's what I said before..... You do know I had SA8's 4 months before they shipped and help develop them right? There is only 1 person that knows more about SA8's than me, and that's the person that designed it. It's not a matter of smaller sub vs bigger sub, it's THAT sub in particular when tuned below 35 hz loses output very quickly across the board. The difference between a 30 hz tune and 35 hz tune in the same box was 5 dB peaking within a few hz. When the Fs is 44 hz, you can't expect it to play 30 with exceptional output, even in a 30 hz tune. I'd hate to talk about something on the forum and actually have experience with it rather than regurgitating simulated graphs and what other people say that also have no experience....... My 10s have no problem performing well playing in the low 20s htz range with considerable amount of spl too ... To the op, i rather see 4 8s rather than 3 ... Just my suggestion please ...