Classical music has sometimes appeared in bluegrass, and the instruments thought of as part of the bluegrass ensemble -- the mandolin and the guitar, especially, but even the banjo, most often in its tamer varieties -- have occasionally been deployed in semi-classical settings. It's safe to say, however, that the banjo has never ventured as far into the classical sphere as it does with John Bullard. Raised in rural Virginia in the early 1970s, Bullard gained his first exposure to the banjo like so many other players when he was riding with his father in a pickup truck and hear...