At the Darmstadt Holiday Courses in 1972, in a lecture entitled 'Tendenzen zu einer neuartigen Tonalität' (Tendencies towards a New Tonality), he suggested a thorough turnaround of modernism, also pointing to "Pop Art" and new "Romanticism", thus also initiating a number of misunderstood and by many other composers taken up changes in the stylistics of the 1970s ("Neuromanticism").
As a composer, he himself took up influences from Pop Art and American stylistics at an early stage and distinguished himself above all in the field of polyrhythmic.
From 1980 onwards Dadelsen gradually developed a consistently polyrhythmic style ("flexible beats") together with the composer Babette Koblenz.
In 1998–2004 followed the direction and conception of the Hamburg chamber music festival "P0P – Pur oder Plus"; In 1999 together with Manfred Reichert he led the conception and direction of the Karlsruhe Bob Dylan Festival "Beethoven listens to Bob Dylan".
From 2007 until his retirement in 2014, von Dadelsen worked as a music teacher at the Hegau-Gymnasium Singen, where he also led the Big Band.