This Fledermaus was produced just before the end of the war. During the chaos at the end of the war the sound-track was lost and had to be re-recorded after the war with the then available equipment and with the same cast. This according to Neue Zürcher Zeitung in about 1948. I saw it several times in Zürich at this time. Modern technology has now done much to improve the sound quality. I approve of a man, in this case non-singing Siegfried Breuer, playing the roll of Prinz Orlowsky. Breuer makes a good prince. Some years later Peter Alexander produced a Fledermaus in which a tenor played/sang the role. This worked very well, tho the rest was not very good. A man should play/sing the title roll in Der Rosenkavalier. I know that these rolls were written for a castrato, but, in the case of Fledermaus, an operette contralto won't do - I have heard/seen several such performances and the poor ladies were hardly audible. You need a powerful contralto and tall, broad-shouldered and flat-chested operatic or wagnerian contraltos are rare. After all, the producers/directors are in the business of creating an illusion for both eye and ear, which is why I have written "play/sing" - too often the singing is good, the acting week.