“Crate diggers”—music obsessives who thumb through endless cartons of vinyl records in search of overlooked gems—are behind one of the most intriguing labels operating today, the Chicago-based Numero Group. Dedicated to unearthing lost musical treasures—primarily in the realms of soul, funk, and gospel—the eight-year-old label has amassed legions of devoted fans.

Numero Group's office in Chicago's Little Village neighborhood, a small two-story house that was originally the home of one of the co-founders