Jung learned to play the piano with among others, and later the violin and the viola, performing in public for the first time in 1935. He studied social sciences in Frankfurt. As a student, he cofounded the in 1941, playing as the group's pianist with , Emil Mangelsdorff, and Charly Petry. In 1943, he also learned to play the double bass, and served as the group's bassist from 1945 to 1948 in the Hotclub Sextet. The broadcaster Hessischer Rundfunk aired in 1946/47 a show with him as the solo pianist, playing in the style of Teddy Wilson.
