The A-major Sonata D 664 preserves a little mystery: to the present day, it is still not entirely clear whether it came into being in 1825 or if it was already composed six years earlier. Its stylistic proximity to the “Trout Quintet” D 667, which was almost certainly composed in the autumn of 1819, speaks for the latter. There is no doubt, however, about the sonata’s enduring popularity, which it owes to its cheerful tone and presumably also to its manageable length: it has only three movements...