On the cusp of releasing “Born in the Echoes,” the eighth studio album featuring guest appearances by a varied roster of guests, including Beck, Q-Tip and St. Vincent (the latter under her birth name, Annie Clark), Chemical Brothers have hit the road to drop their patented big beats and bumping bass showcases. Well, one of them has, anyway. While he’s still half of the group, Ed Simons announced in November that he’s no longer part of its touring makeup, leaving those duties to soul Brother Tom Rowlands and visual collaborator Adam Smith while he continues academic work begun a few years ago.