Eddie Prevost, in No Sound is Innocent:
"In 1965, AMM began a radically different kind of music-making. The prevalent notions of musical theory, practice, hierarchy, and structure (thematic reference, jumping-off points--for example the 'head' arrangements from which improvisation lifed off--and even the relatively informal criteria of the then 'free jazz' movement) were replaced by the creation of, and engagement with, a sound-world in which there was not even a formal beginning or ending."