His encounter with Carl Orff, with whom he took private composition lessons after World War I, was decisive in determining his choice to turn to music professionally.
From 1920 to 1922, Marx studied composition with Anton Beer-Walbrunn and conducting with Eberhard Schwickerath [de] and Siegmund von Hausegger at the Akademie der Tonkunst in Munich.
The assertions made by Michael Hans Kater in his controversial book The Twisted Muse[2] about Marx's alleged Nazi past are disputed by others.
[3] From 1946 to 1966, Marx taught harmony, counterpoint and composition at the Staatliche Hochschule für Musik in Stuttgart and from 1955 as head of the department for school music.
The cantata Und endet doch alles mit Frieden to words from the novel Hyperion by Friedrich Hölderlin for soloists, choir and orchestra, Op.
Marx names two traits that characterise his music: thrift in the use of means and constructive thinking, and continues: "Next to this is the commitment to melody, which is influenced by the handling of the folk song as well as by the encounter with pre-classical polyphony".