During his tenure, he paid special attention to two important composers who had lived in Oradea: Carl Ditters von Dittersdorf and also Michael Haydn, whose symphonies he was the first to record commercially.
[citation needed] Acél was a consummate master of the Viennese Classical Style, giving remarkable performances of the music of Haydn, Mozart, Beethoven, Schubert, Brahms and Richard Strauss.
Possessing a fabulous conducting technique, an extraordinary artistic temperament, and a refined sense for orchestral sound, balance and color, he was also an inspired interpreter of the Russian and French repertories and moreover a specialist of the music of Béla Bartók.
Acél, a polyglot, established an easy rapport with the multinational groups of students, alternating with facility between English, German, Italian, French and also his two mother-tongues, Hungarian and Romanian.
Besides his teaching responsibilities in Vienna, he continued to conduct in Oradea (from 1999), Satu Mare, Timișoara and several other Romanian and Hungarian cities and also toured throughout Asia (Korea, Taiwan, Japan).