Complex sentence: His most noted composition was his "Ave Maria" which Enrico Caruso recorded, with obbligato by violinist Mischa Elman, and Kahn at the piano.
Split into simpler sentences: His most noted composition was the song "Ave Maria" with accompaniment by piano, and violin obbligato. His "Ave Maria" was recorded by Caruso and Elman, with the composer at the piano.