The typical piano quintet would usually feature a string quartet (two violins, viola, cello) with piano. As Schubert had done for his Trout Quintet, both Hummel and Vaughan Williams replaced one of the violins with double bass, adding power and warmth to the sound. The Vaughan Williams quintet debuted in 1905, yet was not performed a second time until 1995. Once you hear it you will wonder why.