At 27, Mathieu Dufour, the Chicago Symphony Orchestra’s new principal flutist, is one of the youngest section leaders in any major symphony. The Paris native has been a principal player ever since he graduated from France’s national conservatory in Lyon–from 1993 to ’96 in Toulouse and then in the Paris Opera’s pit orchestra. In April ’98 in Paris, Daniel Barenboim asked Dufour to play for him privately–about two months after the CSO’s principal flutist at the time, Donald Peck, publicly announced that he’d retire at the end of the season. Barenboim was duly impressed by Dufour’s flawless intonation and mellifluous phrasing; even though more than a hundred flutists tried out later that spring, it surprised no one when Dufour got the job last January. This fall, only a few concerts into his first season here, it became clear that at long last the CSO once again had a world-class wind section–and on top of that, Dufour has a real camaraderie both with two other relatively new principals, Alex Klein (oboe) and David McGill (bassoon), and with veteran Larry Combs (clarinet). Though trained in the French school of flute playing, which emphasizes elegance and ethereality (think of Debussy’s faun), Dufour has proven marvelously flexible, also displaying a mastery of the darker, plummier tone favored by Germanic composers. This weekend he makes his American solo debut in two concerts with a fine but not superb smaller ensemble, the Chicago Sinfonietta, where he’ll have the spotlight for Mozart’s Flute Concerto no. 1. Paul Freeman, the Sinfonietta’s conductor, is more often effective than inspired, but he deserves praise for his advocacy of neglected composers: in addition to Tchaikovsky’s Symphony no. 2, this program includes 1944’s African Suite by Fela Sowande, a British-educated Nigerian conductor and organist who taught ethnomusicology at Howard University. Sunday, 2:30 PM, Lund Auditorium, Dominican University, 7900 W. Division, River Forest, and Monday, 7:30 PM, Orchestra Hall, Symphony Center, 220 S. Michigan; 312-857-1062.