He became a permanent member of the company in 1950, remaining with that ensemble for his entire career, although he undertook frequent guest appearances elsewhere in Europe and in the UK.

While in Salzburg, he collaborated with Herbert von Karajan conducting the Vienna Philharmonic Orchestra in a production of Mozart's opera Don Giovanni with Leontyne Price and Elisabeth Schwarzkopf.

Included among his acclaimed renditions of sacred works were: Johann Sebastian Bach's "Passions" and Beethoven's Missa Solemnis.

Also included among his recorded performances are: Béla Bartók's Bluebeard's Castle (London Records), Beethoven's Missa solemnis (Deutsche Grammophone), Joseph Haydn's The Creation (Deutsche Grammophon), Mozart's Cosi Fan Tutte and Marriage of Figaro (both EMI), and Mozart's Bastien und Bastienne (Philips).

[14] Critics at Billboard magazine noted that his collaboration with his wife Christa Ludwig in a recording of Bartók's Bluebeard's Castle was delivered with dramatic force and strength.