These iconoclastic Chicagoans have played together in different combinations over the years, but rarely all at once. A few years ago they made a record for Atavistic's Out Trios series, and while the results were uneven--always a risk with improvised music--the range of sounds they produced was astonishing. I was going to list the instruments used on the recording, but that's beside the point: Parker, Drumm, and Zerang are all capable of rendering their gear unrecognizable. And when they're playing in this mode, there's too much happening for the listener to stop and figure out who made what noise: metallic clatter, lacerating sine waves and feedback, and floor-rumbling low end seethe and boil in a shape-shifting mass. It's anyone's guess what they'll sound like here, but considering that these guys are among the most careful listeners and progressive voices in the city the show should be riveting. a 9 PM, Velvet Lounge, 67 E. Cermak, 312-791-9050, $10.