Seated at the grand piano in MIT’s Killian Hall last fall, first-year student Jacqueline Wang played through the lively opening of Mozart’s “Sonata in B-flat major, K.333.” When she’d finished, Mi-Eun Kim, pianist and lecturer in MIT’s Music and Theater Arts Section (MTA), asked her to move to the rear of the hall. Kim tapped at an iPad. Suddenly, the sonata she’d just played poured forth again from the piano — its keys dipping and rising just as they had with Wang’s fingers on them, the resonance of its strings…