The Danish Quartet has reached incredible heights in the course of its 12 years of performing. These four young musicians—three Danes and a Norwegian—have concertized throughout Europe, demonstrating their technical mastery and joy of playing while remaining, in their own words, “simply your friendly neighborhood string quartet with above average amounts of beard.” The group’s typically adventurous program features the second Razumovsky quartet, a Philadelphia premiere by Norwegian composer Rolf Wallin, and a selection of folk tunes from the quartet’s homeland.