Mathieu Dufour, who was appointed the CSO's principal flutist in 1999 at the age of 25, raised the bar on orchestral flute playing. He can both blend with other instruments and project to the back rows of an auditorium, producing an astonishing variety of sounds with perfect intonation and impeccable musicianship, and his tone has clarity and depth that never diminish, even in pianissimo. He regularly performs in concerti and recitals, often as a member of the Chicago Chamber Musicians--13 members of the CSO, Lyric, and local university faculties. Here he's joined by three instrumentalists from the CSO's incomparable wind section--oboist Michael Henoch, bassoonist Dennis Michel, and horn player Gail Williams--along with Lyric clarinetist Susan Warner, who's sitting in for Larry Combs, in a rare performance of Samuel Barber's Summer Music for Wind Quintet. Barber brilliantly captures a lazy summer evening with undulating low notes and jazzy flute and oboe riffs that evolve into a wistful, bluesy lament, then moves into a dancelike section that alternates between somber and joyful. For the rest of the program various CCM ensembles will be joined by guest pianist Earl Wild, at 88 still a remarkable old-school virtuoso. He'll play Brahms's four-hand transcription of the Hungarian Dances with Deborah Sobol of Northwestern, Franck's exquisite Sonata for Violin and Piano with Joseph Genualdi of DePaul, and Beethoven's youthful Piano Trio op. 1, no. 3--not his most profound work, though it has a serene and lovely slow movement--with CSO violinist Jasmine Lin and CSO cellist Stephen Balderston. Wednesday, April 14, 7:30 PM, Harris Theater for Music and Dance, 205 E. Randolph; 312-225-5226 or 312-334-7777.