Listen to Clarinet Sonata in A-Flat Major, Op. 49 No. 1: IV. Prestissimo assai online. Clarinet Sonata in A-Flat Major, Op. 49 No. 1: IV. Prestissimo assai is an English language song and is sung by Stephan Siegenthaler. Clarinet Sonata in A-Flat Major, Op. 49 No. 1: IV. Prestissimo assai, from the album Reger: Integrale Kammermusik für Klarinette, was released in the year 2016. The duration of the song is 4:41. Download English songs online from JioSaavn.