qnli question: PIccolo, contrabassoon, and trombones add to the triumphal finales of what piece by Beethoven? sentence: The Ninth asks for a second pair of horns, for reasons similar to the "Eroica" (four horns has since become standard); Beethoven's use of piccolo, contrabassoon, trombones, and untuned percussion—plus chorus and vocal soloists—in his finale, are his earliest suggestion that the timbral boundaries of symphony should be expanded.