The Kronos Quartet has not grown into a crossover phenom on the strength of its punk haircut and space-age attire alone. Only a decade old, this ensemble is already commanding wide respect as the most incisive, eloquent, and impassioned interpreter of contemporary music--"serious" and otherwise; the trendy accoutrements, along with a puckish sense of humor, are but an affectation that puts its (predominantly young and hip) audiences at ease. For its Ravinia debut, the San Francisco-based thirtyish foursome has slated a typically unpolemical program--a musical Tower of Babel, if you will. The idioms range from post-Bartokian (the somber, two-movement Quartet by Poland's Lutoslawski) to minimalism with an Afro-Brazilian beat ("Pano de Costa" by Tennessean Jon Hassell, the avant-garde jazz trumpeter noted for his experimentation with "fourth world" music) to Balinese-accented neo-primitivism (String Quartet no. 8 by Peter Sculthorpe of Australia). The climax of the evening, however, is likely to be Conquest of the War Demons by Terry Riley, the pioneering minimalist whose latest surge in creativity is very much a response to the Kronos's kinetic (and committed) musicianship. Be sure to stay for the encores and discover yet another ingredient of the quartet's appeal and crossover success. Monday, 8 PM, Murray Theatre, Ravinia Festival, Green Bay and Lake Cook Rds., Highland Park; 728-4642.