Alex Klein, former principal oboist of the Chicago Symphony Orchestra, performs sonatas that signify the oboe’s 20th-century reemergence as a brilliant solo instrument. One of the world’s most famous oboe players, Klein says he waited to acquire a professional lifetime’s worth of experience before putting his stamp on the six works heard here. With pianist Phillip Bush, Klein plays works that he says “define the modern oboe”: sonatas by Camille Saint-Saëns, York Bowen, Henri Dutilleux, Petr Eben, Francis Poulenc, and Eugène Bozza.