Jazz standard and Billy Strayhorn's "Take the 'A' Train" (1941). With the big bands struggling to keep going during World War II, a shift was happening in jazz in favor of smaller groups. Some swing era musicians, such as Louis Jordan, later found popularity in a new kind of music, called "rhythm and blues", that would evolve into rock and roll in the 1950s. Bebop emerged in the early 1940s, with Charlie Parker, Dizzy Gillespie and Thelonious Monk leading the way. It appealed to a more specialized audiences than earlier forms of jazz, with sophisticated harmonies, fast tempos and often virtuoso musicianship.
Horn in jazz compete directly with Basie's hard-swinging blues, the duo capitalized on their contrast from Basie’s sound, playing with a soft and mellow sound. By showcasing their different sound, Ruff and Mitchell continued to get bookings from Birdland to play intermission for other big name groups like Miles Davis, Dizzy Gillespie, Sarah Vaughan, Lester Young, Dinah Washington and others. After working with Claude Thornhill and arranging for his orchestra, he began arranging for Miles Davis. In 1948 the Miles Davis Nonet was formed with a sound completely unlike anything jazz listeners had heard before. The original idea for the nonet was to