During his career, Sistermans premiered important compositions by Johannes Brahms and Gustav Mahler, and also had lieder dedicated to him by Hans Pfitzner, Eugen d'Albert and Alexander von Zemlinsky.
Although he primarily sang roles from the Wagnerian repertoire, Schmedes was also an admired interpreter of Florestan in Beethoven's Fidelio and the title role of Pfitzner's Palestrina.
In the German repertoire he had roles in Pfitzner's Palestrina and Das Herz; Schultze's Schwarzer Peter; Eugen d'Albert's Tiefland, Goetze's Widerspenstigen Zähmung, Jokanaan in Richard Strauss's Salome, and others.
One of his greatest and most acclaimed recordings was that of the great masterwork of Hans Pfitzner, Palestrina, which he recorded under the baton of Rafael Kubelik.
He has recorded the complete orchestral repertoire of Paul Hindemith, Erich Wolfgang Korngold, Hans Pfitzner, and Benjamin Frankel.
Hans Christian Andersen | Hans Holbein the Younger | Hans Zimmer | Hans Werner Henze | Hans Memling | Hans Pfitzner | Hans Küng | Hans Conried | Hans Knappertsbusch | Hans Magnus Enzensberger | Hans-Dietrich Genscher | Hans Blix | Hans Zender | Hans Scholl | Hans Hofmann | Hans Christian Ørsted | Hans Raj Hans | Hans Habe | Hans Baldung | Baron Hans Heinrich Thyssen-Bornemisza | Pfitzner | Hans von Ohain | Hans van Manen | Hans Urs von Balthasar | Hans Sloane | Hans Rosbaud | Hans-Georg Backhaus | Hans-Adam II, Prince of Liechtenstein | Yuvraj Hans | Hans von Halban |
His advocacy of Granville Bantock, Havergal Brian, Dussek, Medtner, Hans Pfitzner, Max Reger, Franz Schmidt, Robert Volkmann and others was as sincere, and informed by an acquaintance with the music as close, as his discussions of Schubert’s piano sonatas or Haydn's string quartets.
As a teacher he exerted great influence; among his pupils were Bernhard Sekles, Ernest Bloch, Vladimir Sokalskyi, Ernst Toch, Roger Quilter, Hans Pfitzner, and Cyril Scott.
He is especially interested in twentieth century music, and, as accompanist, he initiated and let a series of lieder recitals, featuring music by such composers as Schoenberg, Pfitzner, Korngold, Rihm, Hindemith, Bridge, Holst, Rebecca Clarke, Crumb and Argento.
By 1975 the group had built up a repertoire of 120 works, including the complete Beethoven, Schubert, Cherubini and Bartók quartets, and works by Haydn, Mozart, Brahms, Hugo Wolf, Pfitzner, Verdi, Donizetti, Debussy, Smetana, Kodály, Janáček, Hindemith, Alban Berg, Gian Francesco Malipiero, Witold Lutosławski, Milko Kelemen, Wittinger and Horvath.
The choir collaborates with the orchestra Münchner Philharmoniker, and has been conducted by prominent conductors such as Gustav Mahler, Hans Pfitzner, Krzysztof Penderecki, Rudolf Kempe, Herbert von Karajan, Sergiu Celibidache, Carlo Maria Giulini, Seiji Ozawa, Zubin Mehta, Lorin Maazel, Mariss Jansons, James Levine.