Listen to Piano Concerto No. 15 in B-Flat Major, K. 450: I. Allegro (String Quartet Version) online. Piano Concerto No. 15 in B-Flat Major, K. 450: I. Allegro (String Quartet Version) is an Unknown language song and is sung by High Note Maestro. Piano Concerto No. 15 in B-Flat Major, K. 450: I. Allegro (String Quartet Version), from the album Staff, Clef & Note – Timeless and Mood Classical Music, Inspiration to Create, Must Have Amazing Masterpieces, Classics with Authority, Positive Attitude, Personal Development, was released in the year 2015. The duration of the song is 2:20. Download Unknown songs online from JioSaavn.