At Groupmuse NYC, “Cello and Piano Sonatas” places Bohuslav Martinů beside Sergei Rachmaninoff in a single chamber frame. Martinů’s writing, shaped after his 1923 departure from Czechoslovakia for Paris, turns toward lean modern lines and occasional jazz-tinged rhythm, while Rachmaninoff holds to late-Romantic density and long-breathed melody. New York has long served as an American proving ground for both composers, especially Rachmaninoff, who lived and worked in the city’s concert life. Heard together, the program shows how two contemporaries answered the same century with different vocabularies.