Schmahl worked at times as concertmaster of the Rundfunk-Sinfonieorchester Berlin and from 1973 to 1984 as rector of the University of Music and Theatre Leipzig.
[2] After attending secondary school and passing his Abitur in 1949, he studied for two semesters with the violin virtuoso Max Strub at the Hochschule für Musik Detmold.
After the founding of the GDR he moved to Gustav Havemann at the Hochschule für Musik "Hanns Eisler" in East Berlin in 1950.
In 1950, he was a prize winner of a competition of the FDJ[3] and in 1951 he qualified for the III World Festival of Youth and Students in East Berlin.
[4] A study visit led him as the only[5] violinist from the GDR to the Soviet pedagogue and virtuoso David Oistrach at the Moscow Conservatory.
[8] He played chamber music among others works by Igor Stravinsky, Dmitri Shostakovich, Sergei Prokofiev and Hans Werner Henze.
[9] In 1963, Schmahl took on a teaching position and in 1970 a full-time lectureship at the Hochschule für Musik Carl Maria von Weber.