The quartet is considered the authentic interpreters for many late 20th century composers, with a reputation for mastering the most difficult and complex compositions. They rarely improvise as their focus is on working with composers. These composers range from those active in the early 20th century to the present and include Hans Abrahamsen, Thomas AdèsLuciano Berio, John Cage[6Elliott Carter, Franco Donatoni, Pascal Dusapin, Henri Dutilleux, Brian Ferneyhough, Morton Feldman, Georg Friedrich Haas, György Kurtag, Helmut Lachenmann, György Ligeti, Witold Lutoslawski, Wolfgang Rihm, Giacinto Scelsi[10, and Iannis Xenakis.