Fifteen years ago, you'd have had trouble convincing most listeners that four saxophonists performing jazz--without any other instrumental accompaniment--was a musical experience worth investigating; these days, it seems you can't turn around without running into an album by yet another saxophone quartet, from the long-running World and Rova quartets to such new foursomes as England's Itchy Fingers and the 29th Street Saxophone Quartet. Chicago's own entry into the SQ Derby is Saxophonitis, soon to release their debut album on Germany's Sound Aspects label. Ernest Dawkins, Edward Wilkerson, Mwata Bowden, and Ari Brown all lead (or have led) memorable bands of their own, and together they compose a critical mass of the city's most adept new-music reedmen. Saxophonitis falls somewhere between the rigorous cerebralism of Rova and the swagger strut of the WSQ, but those are just guideposts: the group derives its real character from Chicago's Association for the Advancement of Creative Musicians and that organization's deeply emotional brand of free improvisation. Saturday, 8 PM, Village Compound, 2237 E. 79th; 752-2212.