One measure of the brilliance and ubiquity of a timeless pop song is the number of times it's covered by other respected artists, and in that regard, few recent releases have matched Gnarls Barkley's 2006 hit "Crazy."

It seemed as if one of every three bands performing at Lollapalooza that year took a crack at the psychedelic soul/rock/hip-hop hybrid, and others who tackled it included Nelly Furtado, Cat Power, the Raconteurs, Shawn Colvin, Beyonce and Pink Floyd's David Gilmour. None, however, matched the multi-hyphenated musical brilliance and memorable panache of original auteurs DJ Danger Mouse (Brian Burton) and singer Cee-Lo Green.

Now, the duo at the heart of Gnarls Barkley is in the unenviable position of trying to top that accomplishment from their debut album, "St. Elsewhere," which sold 1.3 million copies in the United States and spent 47 weeks on the Billboard albums chart.

To cut to the chase: There is no instant smash like "Crazy" on "The Odd Couple," which arrives in stores Tuesday but is already widely available on the Net. Yet the duo's sophomore album is on the whole every bit as enjoyable as its predecessor, and equally effective as a giddy stylistic romp that also is deliciously dark and atmospheric.

"Got some bad news this morning / Which in turn made my day," Green sings in his endearingly gruff voice on "Who's Gonna Save My Soul," which underscores a love of the depressed and decadent equal to any Gothic vampire. But Gnarls Barkley aren't mere zombies. Later in the same tune, Green adds, "Oh, I'm out of control now," and that's the red herring: His band is always very much in control, crafting 13 tracks that sustain a mood as potent as any great horror director.

Though many critics missed this fact in the rush to laud the relatively atypical "Crazy," "St. Elsewhere" was a concept album akin to "The Dark Side of the Moon" as an account of the many factors that drive people over the edge. "The Odd Couple" continues in this vein, a bit less coherent lyrically but just as inventive musically, and lighter on the spaghetti western soundtrack samples (and with no Violent Femmes cover) but upping the nods to England's proto-mod Northern soul sounds of the mid-'60s.

This makes perfect sense. Anyone who loves outlandish costumes as much as Green has to be a closet mod, and Burton clearly appreciates the wide-open stylistic boundaries of Swinging London in the era when it was just beginning to tune in and turn on, charting a course for the full-fledged psychedelic explosion to follow. (No wonder Gilmour loves this band: It reminds him of his earliest days on the scene.)

Atlantic is pushing the single "Run" as a follow-up to "Crazy," and its frantic vocals and rollicking tempo are among the disc's most upbeat moments; another is the raucous "Nuggets"-influenced garage-rock/freakbeat homage "Whatever." But at a time when many listeners just cherry-pick tracks for their iPods, "The Odd Couple" is best appreciated as a sustained album and a guided tour through two of the more unique creative forces and cheerfully perverse psyches on the current music scene.