Giacinto Scelsi's five string quartets mark as accurate a trail through his development as any of his works. The half-hour-long First Quartet, completed in 1944, is one of the few examples of Scelsi's early style that have not been withdrawn, and its curious mix of modernist influences hardly anticipates the obsessive austerity of his later music. In the four subsequent quartets, from the Second of 1961 to the Fifth of 1985 (his final completed work), Scelsi exploited that self-circumscribed musical world in microscopic and sometimes absorbing detail. The Arditti performances of the quartets, of the String Trio and, with the soprano Michiko Hirayama, of the "seven episodes of an unwritten story of love and death" that make up Khoom (1962) are tremendously intense and committed; whether you respond to the music or not is quite another matter.