for String Sextett. Par MOZART WOLFGANG AMADEUS. For String Sextet (2 Violins, 2 Violas, 2 Cellos, Bass) set of parts. Mozart ’s Sinfonia Concertante for Violin and Viola, K. 364 (320d), is his only complete surviving work in this genre. He wrote it in 1779 after returning from Paris and Mannheim. For two decades it was known only in a few copyists’ manuscripts. The first edition did not appear un…