The graphic notation by John Cage, Earle Brown, Dieter Schnebel and other pioneers of were presented in the Museum im Kulturspeicher Würzburg and in Frankfurt, and were sonically realised in concerts.

In cultural politics, Stahmer was active in Deutscher Musikrat, and was president of the German section of the Internationale Gesellschaft für Neue Musik (IGNM) from 1983 to 1987 and from 2000 to 2002.

[2] After Threnos for viola and piano (1963) and other youthful works, Stahmer found new forms of expression in collaboration with visual artists, partly using electronic means.

Pieces such as There is no return (1998) show that Stahmer's preoccupation with foreign ethnic groups not only has an intrinsic musical effect on his composing, but also includes political commitment to the victims of white tyranny.

In the cycle Songs of a Wood Collector (2009), written in collaboration with the Lebanese poet Fuad Rifka [de], Stahmer uses the Arabic instruments qanun and frame drum.

Stahmer's compositions, including numerous vocal and instrumental solos, were often created in artistic collaboration with musicians such as singer Carla Henius, guitarists Siegfried Behrend, Reinbert Evers and Wolfgang Weigel, violinists Kolja Lessing, Herwig Zack and Florian Meierott [de], accordionist Stefan Hussong as well as specialists for non-European instruments such as the sheng player Wu Wei, Xu Fengxia and Makiko Goto (guzheng/koto), Gilbert Yammine (qanun), drummers Vivi Vassileva and Murat Coşkun [de].

"[9]: 17  Initially influenced by Hindemith, Bartók and Berg, Stahmer searched for new means of expression and developed his own diction by engaging with the visual language of contemporary painters and sculptors.

Inevitably, this led to the dissolution of formal thinking, oriented on classical-romantic types, and to experimenting with open forms, which Stahmer presented in some of the forums of Neue Musik in Germany and abroad.

In a counter-movement, he wrote the musical graphic Birthday Canon for John Cage (1982) and the tape piece Der Stoff dem die Stille ist (1990), countering a lushness of sound decisively with a reduction of means and a withdrawal of expression.

In the early 1970s, Stahmer had turned away from the melodic and harmonic models of the Schönberg school and given space to a renewed way of thinking about form and sound in his work.

Later, he returned to a tonality which operates beyond all functional harmonical connections with the modal sound concepts of "Arabic maqam" (modes) or Far Eastern tunings, and sometimes involves pure (pythagorean) intonation.

According to Stahmer, this reinforces a tendency that was already apparent in earlier works, in which the musical forms unfold more and more from the sonority as the structure of the movement expands and the time sequences are stretched.

Influenced by his own experiences of war and flight, he developed a pacifist basic attitude, which he gave expression to in works such as Quasi un requiem and Singt, Vögel.

If in the aforementioned works from earlier times it was a rather general pacifist attitude, for which he sought out corresponding figures of speech in literature and set excerpts from The Colossus of Maroussi by Henry Miller or The Trojan Women by Euripides to music, later the statement sharpened into an indictment of the building of the Berlin Wall (in Wintermärchen), against the Nazi book burnings in Germany in 1933 (in Saved Leaves) and against South Africa's apartheid policy (in There is no Return).

With their ritualistic form of performance and long duration, these works depart from conventional concert practice and unfold their effect preferably in connection with dance and image projections.