Few jazz musicians can make complexity accessible like guitarist Kurt Rosenwinkel, a vital figure in New York's forward-looking postbop scene who's a lot more interested in harmonic and stylistic exploration than in the sound of his own chops. On Heartcore (Verve, 2003) Rosenwinkel and coproducer Q-Tip (of A Tribe Called Quest) used studio technology to fashion a surprisingly effective jazz-pop hybrid out of lush harmonies and programmed rhythms. On his latest, Deep Song, as on his earlier albums, he puts his faith largely in the advanced interaction of his bandmates, who include pianist Brad Mehldau and saxophonist Joshua Redman. Arrangements constantly shuffle foreground and background; the players dig deep into the possibilities suggested by Rosenwinkel's gorgeous chords and respond with endlessly inventive, fluid counterpoint. His ethereal tone, though clearly influenced by Pat Metheny, is very much his own, and his improvising remains unusually responsive to what's being played around him. He's joined for these shows by longtime collaborator Mark Turner--one of the most impressively lyrical and flexible saxophonists today--along with pianist Kevin Hayes, bassist Joe Martin, and drummer Jochen Rueckert. The band's run began Tuesday and continues nightly through Sunday; see separate Treatment items for more. Fri 9/15, 9 and 11 PM, Jazz Showcase, 59 W. Grand, 312-670-2473, $25.