That is impressive with no eq and smart placement to take advantage of their strengths.
You don't think a strategically place pair of 12" ported subs could do just as well, or even extend deeper, and at higher SPL?
I have a pair of ported 15s and managed pretty flat from 115 hz to about 15 hz.
View attachment 35825View attachment 35824
Apples and oranges tho. I'm in a huge room and have larger subs, plus there's some eq'ing in there too. I have some noise below 20 hz but that's at the edge of human hearing and none of my music has content that deep anyway. Well, maybe a couple of demo cds (including some pipe organ!) I like to play from time to time for
shits n giggles or to show off.