Just for S&G I hooked the HE15 with NO box to my amp with the HE15 coils in series and the amp bridged mono. I thought I'd flex the suspension a little, and didn't expect much in the way of bass. Wow was I surprised. The room shook so much I had to reassure myself that I did indeed disconnect the speaker from my old sub and hook it up to the HE15. My wife asked if it was necessary to shake the floor so much. Interestingly, the gain was at about -15db, and the volume quite low. The best part was the very clean bass that came out. It was very natural sounding with one caveat. The response was very null in certain locations in the room. On-axis with the woofer, response was VERY strong. At about 30 degrees off axis, response was nulled. In the room similar effects were produced. On the room boundary farthest from the sub, bass was also very strong. It would be interesting to map the nulls in the room versus frequency and location. I think that it is most likely that the nulls are in different locations at different frequencies, although to my ears when I found a good spot, the overall system sounded very good. All this makes me wonder if a simple dipole (really free air since there's no baffle at all) woofer could be set up particularly for theater use that was 'focused' on a seating are such as a couch. If the frequency response could be gotten flat just at the seating area, you'd have a very simple, natural sounding sub. I have not heard an IB, but I think this is the sound the IB folks rave about. It would probably make sense to use a few drivers to improve power handling, but it would'nt take up any room to speak of. Anyway, just though I'd share this, it was really interesting and it's easy to try. Vince ps-the overall power to the sub was very low, and if you try this, remember the sub is totally unloaded in this situation, so caution is probably in order..