Whatever happened to the industrial revolution? It started out as a promising amalgamation of heavy metal and dance music in the ’80s and seemed to fizzle out near the dawn of the Internet age. However, Pigface has managed to survive this loud, abrasive habitat for more than a quarter-century. The group doesn’t lack fans — it’s sold more than 20 million records worldwide — or famous alumni, with current and former players hailing from groups such as Kittie and Red Hot Chili Peppers. Seeking to rekindle the industrial fire, the Pigface brain trust pulled out all the stops on its latest disc, Easy Listening, incorporating a total of 34 performers, from Penn Jillette to Moby cohort Greta Brinkman. This collective brings together the seemingly disparate worlds of atmospheric head music and straight-ahead hardcore in a way that satisfies both sides of the brain. Organizers of the United Tour have also booked a host of international industrial unions, including Norway’s Zeromancer, whose masterfully co-opted Wax Trax-style rhythms are putting the genre back on the right Nordic track.