Claim: Kenneth Riegel, an American opera tenor born on April 19, 1938, engaged at the New York City Opera from 1969 to 1974 before making his first appearance at the Salzburg Festival in 1975.
Evidence: Kenneth Riegel (born 19 April 1938) is an American opera tenor. He was engaged at the New York City Opera from 1969 (debut in L'heure espanole, with Karan Armstrong) to 1974. He made his first appearance at the Salzburg Festival in 1975.