Originally a drummer in various jazz ensembles, Müller grew interested in free improvisation and began utilizing various extended techniques. He used contact microphones to amplify his drum set, and has incorporated various electronic effects, sometimes using an iPod or MiniDisc recorder to loop or otherwise process his performances. Increasingly since about 2000 Müller has emphasized electronics, sometimes entirely forgoing percussion. Critic Brian Olewnick describes him as "one of the most fascinating collaborators in contemporary improvised music [...] tending to create subtly modulated sounds of an almost palliative nature; often with an elastically liquid rhythmic sense."[1]