Chopin’s and Rachmaninov’s sonatas have not all that often been coupled on record, though they make good if demanding partners. Two major cello sonatas, each over half an hour long, by two of the greatest of all pianist-composers (if we leave Beethoven out of the reckoning) present problems especially of balance. Each of the two composers used to play his sonata: Sir Charles Hallé has a poignant description of the ailing Chopin settling to his, bent over the keyboard “like a half-opened penknife” but gradually straightening up. Naturally, each also wrote himself a virtuoso piano part, with torrents of notes that make life difficult for the cellist. Balance cannot simply be sorted out by a studio engineer; it is a matter of musical accommodation, at the heart of the invention. By and large, the two artists here manage well, whether serenely listening to one other (as in the two slow movements, which are beautifully done) or, in the two scherzo movements, entering into the competition which is also part of the music. Rachmaninov’s Allegro scherzando, in particular, asks a lot of them, in a battle with the pianist that has the cellist digging into his gruffest register.

Alexander Kniazev has the advantage of a tone whose warmth is not without a certain resiny character that helps him to sound through Nikolai Lugansky’s cascades of notes. Both artists also are in command of the long phrases essential, in particular, to Chopin’s opening Allegro moderato, if it is not to ramble somewhat inconsequentially. There is an attractive fill-up in the Vocalise which Rachmaninov originally wrote for Antonina Nezhdanova, a light coloratura soprano, but which well suits the cello.