There were a lot of trumpeters around in the 1960s, but the Big Four were Miles Davis, Freddie Hubbard, Donald Byrd, and Lee Morgan. Davis was the most outwardly obsessed with innovation and constant forward movement: His 1965-68 quintet exploded hard bop into shards, and while people were still absorbing that band’s ideas, he moved on, bringing in electric keyboards and ultimately going full-on into fusion.