Mastodon bassist/vocalist Troy Sanders stood center stage and belted out unintelligible growls over a bedrock of precision noise. The four-piece "smart metal" band changed tempos on a dime and guitarist/singer Brent Hinds delivered a similar vocal attack.

Hulking shirtless dudes moshed, and a fat joint passed by my nose while I struggled to scribble into my notebook. The State was thick with the sound and feel of high-voltage escapism last Sunday.

The four-headed monster from Atlanta that calls itself Mastodon — the most enthralling heavy metal band to hit the national scene since Metallica went limp — kept the audience on its boot-covered toes with straight-up speed metal spiced with prog-rock permutations that made the older guys in Rush T-shirts nod in approval. Sanders and Hinds unleashed garbled lyrics about chasing "the white whale" from their Herman Melville-influenced breakthrough LP Leviathan (2004). They also barked the tales of giant-slaying that constitute last year's major label debut Blood Mountain (Warner Bros.)

The audience responded with raised devil horns and roars at the conclusion of each song. Mastodon was reaping the rewards of hard-won heavy metal supremacy. Sanders even committed a genre taboo by flashing smiles mid-song at select members of the congregation.

Most in the crowd of about 500, which included only about 50 women, were dressed for the chill of Jannus Landing, where the much-ballyhooed show had been scheduled to take place before ticket sales failed to meet expectations. Inside the State Theatre it was hell hot, with no air circulation at all. The aroma of pot soon gave way to the stench of human sweat and spilled hooch. But the crowd didn't seem to care.

Yes, Mastodon is named after a prehistoric wooly mammoth, messes with odd meters and rapid tempo shifts, and has released a concept album based on Moby Dick. But the group can also lock into a groove and barrel ahead like a locomotive rushing downhill. Mastodon wows the prog-rock nerds and recovering "Dungeons and Dragons" addicts, but then throws down with fuck-it-all attitude and sniper marksmanship.

Converge, which took the stage right before Mastodon, was brutal in the worst way possible. The Boston-based grindcore unit's music is the sonic equivalent of a muscle spasm. It was the kind of aural assault only a masochist could enjoy. On the other hand, opener Priestess, from Montreal, won new fans with their brand of '70s-style stoner rock, which actually included some tunes about chicks.

—Wade Tatangelo

The Chili Peppers are potty-trained and all grown up. Have been for a while. The California quartet that played a handful of unhinged shows at Jannus Landing in the '80s — clad in nothing but adult-size diapers — has become an arena attraction that drew a crowd of nearly 17,000 to the Forum on Sunday night.

The two experiences simply don't compare: a young-and-hungry band making a small, packed-to-the-gills venue pulsate with manic energy and mosh-pit frenzy vs. a seasoned outfit that includes three 44-year-olds (and guitarist John Frusciante, who's 36) playing a cavernous venue fully clothed.

Still, the current Chili Peppers deserve their due. Stalking a huge stage with a dazzling canopy of lights, the band pounded out bruising punk-funk grooves anchored by drummer Chad Smith and bassist Flea (who at least had the good form to play shirtless). Flea pounced around, making like a bobble-head doll from the neck up.

The Chili Peppers took the stage as a trio and launched into a Hendrixian jam led by Frusciante's wah-wah-heavy licks. Frontman Anthony Kiedis then bounded onto the stage, and the quartet busted into the funky grind of "Can't Stop."

Kiedis' spitfire raps were, not surprisingly, unintelligible (although a good portion of the crowd seemed to know them by heart), and his singing was, as always, little more than functional. His surfer/B-boy act has worn a little thin, and he's fond of flying karate kicks à la David Lee Roth.

For me, the grooves got a little numbing after awhile, but the near-sellout crowd was bonkers. "By The Way" elicited a hearty sing-along, and when the band bade their pre-encore farewell at the 90-minute mark, the throng hollered itself hoarse. The Chili Peppers returned with the ballad "Under the Bridge," providing the requisite cellphone-waving moment.

Due to a poor parking strategy and the naïve notion that Gnarls Barkley would certainly not start crispy at the 7:30 ticket time, I only caught about a third of the band's 45-minute set. As 15-minute shows go, it was pretty impressive.

Frontman Cee-Lo, built like a refrigerator, and keyboardist/programmer Danger Mouse were supported by a large ensemble that did its level best to translate Gnarls' computer-built album St. Elsewhere into a live spectacle. The results were muddy but energetic. During "Crazy," the group's compelling, Grammy-nominated hit, the core band was joined by an ensemble of white-clad female string players, who added a sweep of grandeur to the proceedings. After a spirited, but brief, run at the bouncy "Smiley Faces," Gnarls Barkley unceremoniously walked into the wings.

—Eric Snider