Performing a complete Beethoven Sonata cycle is the kind of thing that can come to define a pianist's career. Andras Schiff may be no exception. His own journey through all 32 works has lasted three years, partly because he has approached them with such characteristic rigour.

If any of Beethoven's sonatas reward deeper investigation while eluding easy definition, it is surely the final three. Performing them twice in a single evening, Schiff played them together, with no breaks for applause. Heard this way, they dovetail together so perfectly that it is hard to think of them as separate entities.

Schiff made the first movement of Op 109 into a genial play between sunshine and shadow; the second was brief but tense; the epic third found him capturing the mood swings of these mini-Goldberg Variations seamlessly. Op 110 had a strikingly spacious scherzo. But it was in the almost improvisatory passages of the finale that Schiff was at his most eloquent, freed from being overly conscious of the work's structure.

It's curious that for all his intellectual focus, in performance Schiff sounds less thoughtful than, say, Mitsuko Uchida in this repertoire. He has pondered so extensively on the music's large-scale structures that he can overlook smaller-scale matters of phrasing, especially when the music is at its loudest. The almost garish quality of the notes at the top end of his Fabrini Steinway didn't help - strange, given that he takes such care in matching his pianos to his repertoire. Yet the same energy that tipped some passages into harshness kept the softest moments coiled tight and expectant.

Schiff's performance brought forth the extraordinary musical mind behind these sonatas; they rightly sounded like a precursor of everything in modern piano music. The unassuming close to Op 111, which had opened so explosively, seemed absolutely sufficient; there was nothing more to be said.

· Andras Schiff's lectures on the sonatas can be downloaded exclusively from music.theguardian.com/classical