Listen to I. Maestoso - Allegro online. I. Maestoso - Allegro is an English language song and is sung by Symphonic Masterworks String Quartet and Wolfgang Bach. I. Maestoso - Allegro, from the album Beethoven: String Quartets, Vol. 12, was released in the year 2013. The duration of the song is 6:29. Download English songs online from JioSaavn.