Fred Hersch, for all his passion, is as tender and thoughtful a pianist as there ever was. Julian Lage, an acoustic guitarist in 21st-century jazz, is tender and thoughtful almost by default. Pairing them on stage just makes sense. Though Lage is young enough to be Hersch’s son, they’re united by their instrumental touches, as well as a love of melody, inventive approach to harmony, and bottomless knowledge of jazz history and tradition. Their new duo recording, Free Flying, is as beautiful and empathetic as you’d expect; on the bandstand Hersch and Lage can only be more so.