A s cellist of the Nash Ensemble and the Emerson Quartet, Paul Watkins has immersed himself in almost all the chamber music Beethoven wrote. Now he brings those years of experience to his first recording of the cello sonatas. He approached the pianist Alessio Bax for this project after hearing him play the Moonlight Sonata, and his instinct was good: their playing here seems to come from a shared impulse, unflaggingly eloquent without ever seeming to strive for effect. The artwork for Beethoven: The Sonatas for Piano and Cello Together these five sonatas span Beethoven’s composing life. The earliest two date from around the time of his first piano concertos, and they find Beethoven breaking new ground in the way he writes for cello and keyboard as equal duet partners. Both sonatas have slow, serious introductions leading into extended movements showcasing the virtuosity of the pianist, to which Bax rises with a light, crisp touch.…