Koffler’s arrangements of selected numbers from Mozart. Ein Singspiel in zwei Akten und einem Nachspiel were published in 1923 by Gabor Steiner Verlag. Eminent baritone Hans Duhan was probably history’s first opera singer to write a spectacle for himself and sing the main part in it. The production, with a libretto by Julius Wilhelm and Paul Frank, was enthusiastically received by the Viennese audience, though there were also critical comments after its premiere on 2 June 1923 at Vienna’s Volksoper. The music was described as ‘salon’, with tunes ‘oscillating between Toselli and Richard Strauss, between Reißiger and Eisler’ (Ernst Décsey, ‘“Mozart”, Singspiel von Julius Wilhelm und Paul Frank, Musik von Hans Duhan. Volksoper am 2. Juni’, Neues Wiener Tagblatt, 3 June 1923, 12).

The following numbers for voice and piano were arranged by Koffler: ‘Du Glockenspiel der Liebe’, ‘Es drückt den Menschen manchmal der Schuh’, ‘Leise hör ichs klingen’, and ‘Salzburg! Salzburg’ (cf. Musikalisch-literarischer Monatsbericht, 1924).