Karajan's selection of a lighter soprano voice (Helga Dernesch) as Isolde, paired with an extremely intense Jon Vickers and the unusual balance between orchestra and singers favoured by Karajan was controversial.
Karajans valg af en lettere sopran (Helga Dernesch) som Isolde og en ekstremt intens Jon Vickers samt den usædvanlige balance mellem orkester og sangere, som Karajan foretrak, gjorde indspilningen kontroversiel.