Emerson String Quartet, Intimate Letters (DGG). Leos Janacek’s two quartets, the first inspired by Tolstoy’s “Kreutzer Sonata” and the second by his own complex relationship with the married woman who was the muse of his old age, rank high among the masterpieces of modern classical music. Now the Emerson Quartet has recorded its vibrant, incisive interpretations of both works in an album that serves as a perfect companion piece to the group’s classic 1988 integral version of the Bartók quartets (TT).