It is always gratifying to hear an elegant playing of Beethoven's music by a master perfectionist. Or, as it were, mostly Beethoven, and mostly elegant. The program on Sunday, in Davies Symphony Hall, featured András Schiff in a performance of four Beethoven piano sonatas: Op. 10, Nos. 1, 2, and 3; and Op. 13. There was also a colossal encore, Bach's Partita in C Minor.