Mozart - String Quartet No. 4 in C, K. 157 The six string quartets, K. 155-160, were composed by Wolfgang Amadeus Mozart in late 1772 and early 1773. Because they were composed in Milan while he was working &#111&#110 his opera Lucio Silla, they are popularly known as the Milanese Quartets. Before this set was composed, Mozart had written &#111&#110e earlier st..