You haven't heard of them, but this is one band with big shoulders and plenty of horsepower; then again, what would you expect from an alliance of Chicago and Detroit musicians? Kenneth Green is the pianist, from the Motor City; Dushun Mosley, the Chi-town drummer (best known as one of Ed Wilkerson's Eight Bold Souls), shares responsibility for this puissant sextet, which ripples with avant-soul improvisations over a strong and steady pulse. A promotional description suggests that in this band, "AACM explorations meet Detroit grooves," but in a sense that's exactly backward: the grooves come courtesy of the A.A.C.M. Chicagoans (bassist Harrison Bankhead and drummer Mosley), while it's the front line that hails from Tiger Town, with impressive outpourings from trombonist William Townley and Michael Carey on flute. At two recent Chicago performances, Green-Mosley served up challenging and exciting music, in a grand array of moods and tempi--without forgetting to swing. Add in the opportunity to hear who's saying what these days in Detroit, a city of rich jazz lore, and the Complex becomes a fairly simple choice. Saturday, 8 PM, Southend Musicworks, 1313 S. Wabash; 939-2848.