Emerson String Quartet Petroc Trelawny presents a series of three concerts recorded at London's Wigmore Hall by one of the world's most distinguished string quartets. Each concert is based around the three Beethoven 'Rasumovsky' Quartets and also includes music by Bach and a recent work by a composer closely associated with the group. 1/3. A quartet from the 1980s by leading German composer Wolfgang Rihm.