Rob Mazurek in the early 1990s he played hard bop with his first quartet. In 1996, Mazurek founded a workshop at Chicago jazz club The Green Mill called Chicago Underground for the performance of avant-garde, improvisatory jazz. By 1998 he a new ensemble had formed around this idea. Mazurek continued to form groups under the Chicago Underground umbrella, performing as the Chicago Underground Duo and Chicago Underground Quartet. Mazurek would continue experimenting with his laptop-based project Orton Socket. In 2005, he put together an ensemble called the Exploding Star Orchestra for concerts in Millennium Park. In 2006, he moved to Brazil, and founded a new ensemble, the São Paulo Underground.