Rafael Kubelík’s sure-handed 1970 reading of Janačék’s Sinfonietta is peerless, gliding the Bavarian Radio Symphony Orchestra through its minefield of abrupt metric shifts, whipsawing woodwind passagework, and intrinsic sonic imbalances (the score calls for no fewer than 25 brass instruments) without ever smoothing over the rough edges that make it so idiosyncratically brilliant.