The Chicago Symphony Orchestra's showcase for new-music chamber works, the "Music Now" series, is slowly but surely moving into the 21st century. Every composer represented at this week's season opener--from 85-year-old American iconoclast George Perle to Korean-born Unsuk Chin, youngest of the bunch at 39--is still alive, and two of the five works are being performed for the first time. CSO composer in residence Augusta Read Thomas assembled the program, and though it understandably favors professional composers, it also features a piece from Max Raimi, whose principal vocation is as a violist for the CSO. Raimi, a cousin of movie director Sam, has been writing music since age seven; in college he concentrated on performance, partly because he found atonal composition--at the time practically an academic orthodoxy--to be contemptuous of performers and divorced from popular culture. In his own works, unsurprisingly, he tries to counterbalance those trends. Music for Friends and Colleagues, a ten-minute piece scored for the unusual combination of oboe, flute, and viola, will be premiered here by three of Raimi's onstage neighbors from the CSO: principal oboist Alex Klein, principal flutist Mathieu Dufour, and violist Karen Dirks. Klein and Dufour seem to have no technical limitations at all, and Music spotlights an extraordinary strength of each--Klein has such tremendous breath control that on an extended solo with no break for air he can finish as confidently as he began; Dufour can create radiant tone colors, even playing sotto voce. In Raimi's score the flute occasionally dips below the oboe for several measures at a time, reversing their customary hierarchy of pitch and creating an unusual combination of timbres. He knows how to please a crowd--his Elegy, performed by the CSO two years ago, is a perfect example--and the titles of the piece's four sections hint at a welcome exuberance and humor: "Congestion on the Lakefront Bike Path," "Contents Include One Tone Row." Also on the program: Dutilleux's Ainsi la nuit for string quartet, featuring Raimi on viola; Perle's rigorous Six New Etudes for piano; Poul Ruders's craggy and intense From Four Compositions: Composition no. 1; and the evening's other premiere, Chin's Acrostic-Wordplay. Cliff Colnot conducts a chamber ensemble of mostly CSO musicians; other soloists include soprano Susan Narucki and pianist Amy Briggs Dissanayake. Tuesday, December 12, 8 PM, Buntrock Hall, Symphony Center, 220 S. Michigan; 312-294-3000 or 800-223-7114.