During a concerto performance at the Chicago Symphony Orchestra's Shostakovich festival in 1999, violinist Maxim Vengerov played with such ferocity that he broke a string--and without losing his composure, he simply borrowed the concertmaster's instrument and picked up where he'd left off. The Siberian-born Vengerov, now 27, displays an uncommon maturity for a virtuoso so young, but that shouldn't be a surprise--he started learning the core repertoire at age 6, won a major competition at 10, and had debuted with most of the world's major orchestras before he turned 20. He's been compared to the great Jascha Heifetz for the lyrical way he brings out the emotion in a score, though he's notably more assertive than his countryman. Vengerov's rapturous, incandescent sound is especially suited to Romantic and early-20th-century works, as he proves vividly on his latest CD, Vengerov & Virtuosi (EMI Classics), recorded with a group of 11 Israeli violinists and pianist Vag Papian. Lately, however, he's gone Baroque: though the Russian system he was schooled in doesn't have much use for historical re-creations, he's been flying in the face of his training, delivering historically authentic performances on a period instrument. (Baroque violins are pitched a bit lower than their modern counterparts, with a flatter fingerboard and gut strings instead of steel.) Vengerov performs at the CSO's season opener on Friday, under the direction of Daniel Barenboim; at press time the program was being modified to acknowledge the recent attacks in New York and Washington. The same music will be repeated Saturday evening during Symphony Center's free 13-hour "Day of Music"; earlier in the day, as part of the same event, Vengerov will take up a Baroque violin to play two solo Bach pieces. Friday, September 21, 8:30 PM, and Saturday, September 22, noon (recital) and 7 PM (CSO concert), Orchestra Hall, Symphony Center, 220 S. Michigan; 312-294-3000.