MB, not sure how old or what version of the BS-1 you have, but when I auditioned it 4 years ago, I hated it, twice. For some reason, I really wanted to like it, but couldn't bring myself to, even the second time around. The best way to describe my experiences was it sounded "honky". It had all the stereotypical bad atributes of paper woofers, and it was very evident when you compare the BS-1 directly with the larger Loth-X towers.If I remember correctly, the woofer runs without XO, but the tweeter has a cap in series. The 1-PI is a similar speaker with difference being the woofer is rolled off lower with a single coil at about 4KHz opposed to running free up to 10kHz. In my opinion, the 1-PI is a much better sounding speaker. I bet if you did sell your BS-1, you'll get enough money back to build at least two pairs of One-PI's.
Gar.