The Chicago Chamber Musicians begin the new season with a program of Mendelssohn, Dvorak, and Janacek. Mendelssohn's String Quintet no. 2, op. 87, written just two years before his death, has much of the passionate intensity of his early works, and it consistently displays his mastery of counterpoint. The opening has the same spirit as his string octet; the second movement is a light, playful scherzo with wonderful syncopation, and the pathos and quiet dignity of the lento adagio recalls many slow movements of Beethoven. Another striking slow movement is found in Dvorak's Piano Trio in E Minor, the Dumky, the name for a Slavic folk song that alternates between sad and happy. The simple and sincere third movement is pure magic, capturing the essence of a traditional Bohemian song without quoting one. Janacek's wind sextet Mladi ("Youth") is also based on folk music, this time Moravian. Composed in 1924, near the end of Janacek's life, its four short movements are a joyful childhood reminiscence, filled with unusual and difficult-to-execute passages that reflect the rhythms of his native Czech. Joining the reliably good CCM regulars--Joseph Genualdi, Jasmine Lin, Rami Solomonow, Michael Henoch, Larry Combs, Dennis Michel, Gail Williams, and Deborah Sobol--are four guest artists, violist Roger Chase, bass clarinetist Wagner Campos, flutist Alyce Johnson, and cellist Clancy Newman, who won first prize at the 2001 Naumburg Competition. Sunday 19, 7:30 PM, Pick-Staiger Concert Hall, Northwestern University, 50 Arts Circle Dr., Evanston, 312-692-9000 or 312-225-5226, $18-$36. See also Monday.