Mozart's 'Dissonance' Quartet is the last of a set of six famously dedicated by Mozart to his 'very dear friend' Joseph Haydn. Soon after he arrived in Vienna in 1781, Mozart came to know Haydn's recently published Op. 33 set of innovatory string quartets which, said Haydn, had been composed in ‘a new and special way'. It was no idle boast. Not only more concentrated and sophisticated than any previous string quartet, the Op. 33s also employed all four instruments in a more equal, conversational style than ever before.

For Mozart, responding to the Op. 33s with his own set of quartets became a longer and more arduous compositional challenge than any other he ever undertook. The 'Dissonance' got its nickname in the 19th-century, well after Mozart's death, on account of its mysterious slow introduction, with its complex and unsettling harmonies. It caps the set of six which impressed its dedicatee so much that, shortly after the 1785 premiere, Haydn declared to Leopold Mozart that 'Before God and as an honest man, I tell you that your son is the greatest composer known to me either in person or by name.'