The XS—an acronym that was a phonetic play on the word “excess”—subwoofer was a product that came into existence almost as a whim. 

At lower volumes, the subwoofer extended to below 10Hz, a full octave lower than what most experts believe is audible. But ears were not necessary to perceive the effect of the XS playing 10Hz; anyone anywhere near the room could feel the bass. The sensation was gut shaking, the internal abdomen being the precise location where the effect was felt