“Touring has become punishingly expensive for small orchestras, and the days of a concert or two each year in downtown Chicago are long gone for the Saint Paul musicians. But the ensemble, founded nearly 50 years ago, has always been eager to experiment. Tonight, with a concert at the University of Chicago’s Mandel Hall, they are trying something completely different, a three-year Chicago residency that will take them into South Side elementary schools and the university’s music classrooms as well as Mandel.”