I'm trying to remember whether I posted any pictures of my setup, and really am not sure. I just did a quick search and can't find any. I joined the forum when I was searching for information, was hot and heavy in it until my system was up and running, then faded from view.
I originally had thought to build a monster sub, perhaps one or two in a sonotube, but when I started reading about this radical new idea that was still in the grass roots period, it gradually took over my plans. For the price of four 15" drivers that I got a great deal on as close-outs, some scrap mdf I had lying around already, and a fairly cheap Behrenger pro amp I bought on sale at Amazon, I have an extremely powerful, yet accurate low range complement to the other six speakers. No boom, buzz or harsh notes, just low, low, tight bass. Music sounds so good on the system, I am surprised every time I put some on.
You probably know that the bigger the speaker box, the more accurate the sound. But there are limits to enclosure sizes for nearly anybody. With this system, you cut a hole between the listening room and some conveniently placed room adjacent to it (attic, garage, even an outside wall) which is reasonably sealed off from the other room. Then, by placing the drivers with the opening on the back side to the other room, you have, in effect, created a huge box for your speaker. Actually, the sound is the same in both rooms. You don't need great power because multiple, large drivers are very efficent, and the sound has to be heard to be believed.
The IB web site is golden. All your answers should be there, if you are willing to wade through the stuff.