After completing his studies at Verviers and Namur, and then in the Vosges department at the seminary of Saint-Dié and the Faculty of Arts of Nancy, de Nys was ordained priest in 1941 and taught literature and philology at Épinal for a few years.
From then on, it was in a veritable parallel career of musicologist that de Nys launched himself in the early 1950s, and his many activities in this field made him an essential figure of musical life in France during the second half of the twentieth century.
From that time onwards, he was also a radio man, producing programs at the Saarländischer Rundfunk and the Radiodiffusion-Télévision Française; he was thus the host of Sinfonia Sacra with Jean Witold[2] or else with Armand Panigel in the famous Tribune des Critiques de disques [fr].
He actively collaborated in the series "Les Discophiles français", directed by Henri Screpel,[3] quickly became a close friend of the Erato company, and joined André Charlin in 1959, of whom he was the artistic director at the Centre d'Enregistrement des Champs-Élysées,[4] several titles receiving the Grand Prix du Disque.
Co-founder of the "Musique en Wallonie" then heavily involved in the Koch-Schwann label,[5] in 1961, he founded with Hélène Salomé[6] the Cultural Centre of Valprivas, dedicated to musicological research and now possessing an exceptional library and discothèque.