These revered chamber musicians, the German viola player Tabea Zimmermann and the Russian-American pianist Kirill Gerstein, have chosen these three sonatas with immense care: each was written late in the composer's life, each originally composed for an instrument other than the viola. Brahms's F minor Sonata (for clarinet) exploits the darkest colours and lowest range of the viola, and suits its yearning mood, especially in the hands of a duo who have already recorded the companion E flat Sonata. The lyricism of Schubert's Arpeggione (for the six-stringed, cello-like instrument) and the melodic generosity of the Franck (originally for violin) gain new vigour in these fiery performances.