Listen to Piano Quartet in E-Flat Major, Op. 47: I. Sostenuto assai - Allegro ma non troppo online. Piano Quartet in E-Flat Major, Op. 47: I. Sostenuto assai - Allegro ma non troppo is an English language song and is sung by Gordan Nikolitch. Piano Quartet in E-Flat Major, Op. 47: I. Sostenuto assai - Allegro ma non troppo, from the album Schumann Project: Complete Chamber Music With Piano, was released in the year 2013. The duration of the song is 8:54. Download English songs online from JioSaavn.