Hi Schotter,
The TBI offers a single unit (amp and speaker in a single box) and a passive speaker unit (same size box) that is driven by its own stand alone amp (so it is still an active, powered sub with all the dialing in flexibility that this implies ...this is the unit I opted for). Both have line in and speaker level inputs.
One worked perfectly well. There was no shortage of tight, fast bass at all. In fact, I had the volume of the sub set very low (almost off, actually). The problem for me was one of placement. I couldn't place the sub between the speakers (doors on my stand swing out that way). I could only place it off to one side or the other. It still sounded very good, but when I put a second sub on the other side (both located out into the room beside my Super 3s), the bass just locked in perfectly.
If your room isn't huge, one sub will work very well (especially if you can place it in between the speakers). Don't think you will be wanting for bass...it will be there in spades. Two are better (in a qualitative more than a quantitative way), but that is true of all subs anyway, not just the TBI.
The beauty of it is, you don't have to choose now if you get the separate amp and sub combo. The single amp will drive both subs, so you can always add a second sub unit if you feel like it later on.
There are bigger (and more expensive) subs that can shake loose the floorboards in your home, but I haven't heard any as tight and musically tuneful (and I used to own a pair of Kinergetics subs 'back in the day').
Word of warning: once you hear the Omegas with the sub, you won't be able to listen to them without one. This is not to slight them at all, but there is only so much a little fostex can do by its lonesome. But marry the speed, snap and imaging of that driver to the speed and rock solid foundation the TBI provides, and you have a serious full range system.
Good luck and let me know if there is any other info you need!
