The decisive break-through for Gál came with the great success of his second opera, Die Heilige Ente ('The Sacred Duck'), a lyrical comic opera in a Chinese setting, which had its première in Düsseldorf in April 1923 under Georg Szell, and was published as his Op. 15 by Universal Edition. It was immediately taken up by another six theatres and was eventually performed with continued success in some twenty theatres, including Breslau, Weimar, Aachen, Chemnitz, Kassel, Königsberg, Prague and Berlin, during the next ten years. It was performed on Vienna Radio in 1929 - the first modern opera to be staged by the station. The principal tenor role was sung in several of these performances by the well-known opera singer Josef Witt. The work was still in the repertoire of German opera houses in 1933, when its successful run came to an abrupt end as a result of the political circumstances. Die Heilige Ente was Gál's first opera-collaboration with the librettist Karl Michael von Levetzow, whom he had met during his work at the Neue Wiener Bühne, and for whose play Ruth he had composed the incidental music. Richard Strauss had said: "If I hadn't found Hofmannsthal, I would have liked to work with Levetzow" [quoted from Waldstein, Hans Gál Vienna 1965 p. 40]