Music Director Peter Oundjian begins this all-Mozart marvel with a mysterious serenade for winds, which broods before turning suddenly buoyant. At the keyboard for Mozart’s Piano Concerto No. 20 is Tony Siqi Yun, a nuanced performer who plays with “every note personalized” (Musical America). Closing this revel of Mozart’s genius is his Haffner Symphony, a staggering work of energy and invention.