Beethoven’s String Quintet is a bit of a pivot for the composer: he composed the work in 1801, and it serves as a transition from his first creative period to his second, containing elements and style from both. Like a number of works from his portfolio, in the String Quintet Beethoven masks his awareness that he is growing deaf with generally optimistic music. We’ll hear it tonight at 7, our Evening Masterwork, on Classical WSMR 89.1 and 103.9.