After the runaway success of Dig Your Own Hole, The Chemical Brothers made big beat even bigger by adding a touch of '60s acid to their acid house. Their psychedelic impulses run free on "The Sunshine Underground" and "Let Forever Be," a winking Beatles impersonation featuring Oasis' Noel Gallagher, and they return to pummeling rave anthems with "Under the Influence" and "Hey Boy Hey Girl." On the gorgeous "Asleep from Day," featuring a hushed Hope Sandoval, they take the opposite tack, proving that whispers can speak louder than bombast.