m-db The Golden Flutes extended the bass without disturbing the midrange. They were used in the tape loop - so no long cables were needed. They also needed a wall-wart for power. I always had a hard time knowing if they were actually doing anything. The AC-DC song I mentioned made me realize they worked very well. They didn't ever cause any harm to the speakers. I think they just flattened the frequency response.
Speakers with deep/powerful bass
I used to have a system with large speakers. Each speaker had two 12" woofers. When I would play Hard as a Rock from the AC-DC BallBreaker CD there was a moment at 35 seconds into the song when it felt like someone was jumping on the floor behind me. This would only happen if my JPS Labs Golden Flutes were looped into the system, and it was playing very loud. Without the Golden Flutes it didn't happen. It was a truly frightening experience the first time it happened, because I was home alone. Has anyone else had anything like this occur?