The rear unique loudspeakers connection of The Gallo Reference III. This looks liked biwiring, but it is NOT.
The upper speaker cable connection is the usuall input for driving the fullrange of the speaker, tweeter, midrange and woofer (34hz-50khz)
The lower speaker cable connection is directly connected to the 2nd voice coil of the woofer only and when connected a a subwoofer bass amp with a low-pass filter (like the Gallo Reference3 SA), can extend the lower-end repsonse to 22hz!