Kristian Bezuidenhout plays an 1822 Viennese instrument by Anton Walter and Sons, Viktoria Mullova’s Guadagnini is gut-strung. The sound, in these familiar pieces, has a startling clarity and range of colour. In the opening Allegro of Sonata No 3, for instance, we hear clearly how each of the piano’s registers has a different tonal character – some left-hand passages that often appear ungainly on a modern instrument emerge here with a rich, bassoon-like timbre. And Bezuidenhout exploits to the full his piano’s special effects when, just before the recapitulation, the moderator pedal (interposing a strip of felt between hammers and strings) takes us into a dark, romantic forest (tr 1, 5'31").

The other quick movements give a similarly lively, colourful impression. Mullova’s tone has enough variety and character not to need more than occasional touches of vibrato. The high spot is the first movement of the Kreutzer, which combines excitement and passion with especially clear articulation. Bezuidenhout remembers that pianists in Beethoven’s day would often spread chords, and he and Mullova both add to the ebullient feeling with improvised flourishes. My one slight disappointment concerns Sonata No 3’s Adagio – elegantly played and with beautiful tone but too cool for my taste. Surely these expansive, sustained melodies were intended to have a powerful emotional charge. The Andante theme in the Kreutzer similarly seems rather too impersonal but once the variations start the doubts vanish; the minore variation, dark and brooding, is followed by a final transformation where both violin and piano, playing in their high registers, seem to have entered a magical Hoffmannesque fairyland.