They were professionals who respected each other and each other’s music. I think Haydn relished the challenge of dealing with this beloved newcomer.
This is Mozart at his very naughtiest. The introduction to the first movement uses the kind of dissonance that became the standard musical language after World War I, which is why it is known as the “Dissonance Quartet.”
I saw the Emerson Quartet program this piece on the same program as a Shostakovich quartet in 1992 at the University of Washington, and as they began the dissonant introduction, I could see the audience’s confusion as to which piece it was hearing. I got a kick out of that, but then I have a mischievous sense of humor.