Girlpool made their mark with a spare, simple sound - two guitars and two voices, with absolutely nothing else accompanying them. It was an original, intimate sound, and it made the two sound like they were united against the rest of the world. But on their new album, Powerplant, they’re trying something else. They’re playing with a full band. The 12 tracks that compose Powerplant grow and burn with greater fire than the duo have possessed heretofore.