Kassar has composed the musical score for two plays by Jalal Khoury, Hindiyeh (2001) and al Rafiq Sej’an (1976) and contributed to the script for the film Les petites Guerres (1982) by Maroun Bagdadi. The highlight of his journey as a music explorer has been the acquisition of the Annani Arab Music Collection, the largest music archive in Egypt, and the subsequent establishment of AMAR in 2009. As a lawyer, he specialised in Lebanese and French law at Université Saint- Joseph de Beyrouth, Beirut, where he graduated in 1971, and pursued a career as a lawyer. From a young age, he attended the Lebanese Conservatory, where he took classes in western classical music and learned to play the flute.