Piano Quartet,String Ensemble Cello,Piano,Viola,Violin - Level 3 - Digital Download SKU: A0.532101 Composed by F. Sor (1778-1839). Arranged by Klas Krantz. Classical,Romantic Period. Score and parts. 11 pages. Amadeus Music #3000251. Published by Amadeus Music (A0.532101). For piano and string quartet, score and parts. Fernando Sor (1778 – 1839) was a Spanish guitarist and composer, born in Barcelona. In Spain he is sometimes known as the Beethoven of the Guitar. The guitar part is originally a study by F. Sor for guitar solo.