Kunz studied with T. Lierhammer and made his debut in 1933 as Osmin. He was a member of the Opera ensembles at Troppau (= Opava , Czech Rep.) and Plauen (Germany), and from 1937-41 at Breslau (today's Wroclaw, Poland). He joined the Wiener Staatsoper ensemble 1941 where he soon got very popular. He was a part of the famous "Wiener Mozartensemble" of the 40s and 50s. Between 1942 and 1960 he appeared at the Salzburger Festspiele virtually every year. He appeared at Bayreuth in 1943 and again in 1951 as Beckmesser. He was a guest to the Teatro Colon (Buenos Aires), the Metropolitan Opera (New York), Tokyo and the Glyndebourne Festival. His career at the Wiener Staatsoper continued until 1976, and he even appeared in some character roles until the mid-80s. His repertoire included Italian buffo parts, operetta roles and Viennese Song.
His roles include
Danilo (Lehár: Die lustige Witwe)
Guglielmo (Mozart: Così fan tutte)
Leporello (Mozart: Don Giovanni)
Osmin (Mozart: Die Entführung aus dem Serail)
Figaro (Mozart: Le nozze di Figaro)
Papageno (Mozart: Die Zauberflöte)
Falke (J. Strauß jr.: Die Fledermaus)
Beckmesser (Wagner: Die Meistersinger von Nürnberg)