The salon-like ambiance was ideal for Beethoven at his most Schubertian: Piano Sonata No. 27 in E Minor, Op. 90, a two-movement piece from the composer’s “late-middle” (or some could argue, “early-late”) period. Far from the bombast of the Appasionata, the first movement of Op. 90, “Lively, with feeling and expression throughout,” finds the composer turning inward, examining — through an expansive sense of melody that points the way not only for Schubert, but Romantic composers in general — the dichotomies of existence, the positive and negative implications of each musical germ. And by the second movement, a lilting rondo “To be played no too fast and very songfully,” it was clear that melody — not only Kissin’s plush, versatile voicing in the keys, but his free flowing eloquence in sculpting and shaping phrases — was the star of this show.