Muse, Hallam FM Arena, Sheffield<br/>3OH!3, Millennium Music Hall, Cardiff

This band don't do small, and they don't do subtle. As the gig begins I am staring up at three giant illuminated tenement towers when they suddenly rip down the middle to reveal the three members of Muse – the bird-like Matt Bellamy, the elf-like Dom Howard and the dad-like Chris Wolstenholme – perched on podiums 20ft above our heads like the goodies inside the world's biggest Christmas cracker.

The we-are-Übermensch visual message is so grin-inducing that you almost don't notice that they're playing "Uprising", the revolutionary lead single from The Resistance, the trio's most political album. "They will not control us/We will be victorious," Bellamy croons, and mutters: "It's time the fat cats had a heart attack."

What's frustrating about Muse is their unwillingness to dish dirt, name names or nail their colours to a specific mast. Then again, if Bellamy can at least persuade a percentage of his hordes to be less passive and more questioning, he's made a difference.

If "Uprising" is Billy Idol's "White Wedding" through a Goldfrapp filter, then "Supermassive Black Hole" is essentially Prince's "Kiss" played by Metallica. "Guiding Light" is Ultravox's "Vienna" played by Queen, and "United States of Eurasia" is "We Are the Champions" played by a crazed conspiracy theorist, and so on.

What's guaranteed about Muse is that they will always rock, and it will always be baroque. From the big bastard riff of "New Born" through the cathartic, lung-bursting double of "Plug in Baby" and "Time is Running Out" to the berserk cavalry charge finale of "Knights of Cydonia".

You can also always be sure that their shtick is never knowingly underdone, from the duelling green lasers to the big perspex piano to Bellamy's shamelessly stagey way of drrrawing ouuut a syllable.

Breaking news: Muse in "still brilliant live band" shocker. Now, from the awesome to the merely "ossum". It's always gratifying, in some minor way, when a band who are stadium-fillers in the US aren't even club-fillers over here. When they do visit these shores, their profile is roughly on a par with other foreign acts who are punted as "The Russian Britney" but who only really play to expats in London theatres. For the time being, this is the status of 3OH!3, a duo of gonzo white rappers at the forefront of the "crunk-core" wave, whose main inspirations appear to be the Beasties before Buddhism and The Bloodhound Gang on "The Bad Touch", and whose double-handed gang sign, which involves making the shape of a gaping orifice by touching the tips of your thumbs and index fingers, leaving three spare fingers either side (three, O, three ... see what they did there?), threatens to eclipse any of their songs.

Americans, by and large, have never "got" techno, but if you stick a couple of clowns up front yelling about bitches and the like, they love it. Back home, 3OH!3 are the biggest thing to come out of Colorado since South Park. In Cardiff on a rainy Monday, they struggle to fill an 800-capacity club with a crowd so young that you need special wristbands to get served at the bar.

3OH!3 are Sean Foreman, a compact little guy with Hollywood teeth, and Nathaniel Motte, a tall skinny guy with horrible hair. They both have degrees in physics, and they both look slightly too old to be doing this.

For shows they employ a live drummer and guitarist, but the foremost element in their Limp Bizkit-go-to-clubland noise is the pre-recorded rave riffs on the backing track. Strip away all the jumping and shouting, and their actual rhymes are hopeless. The line that always gets quoted (from the single "Don't Trust Me"), is "Tell your boyfriend, if he says he's got beef/That I'm a vegetarian and I ain't fucking scared of him". But is that actually that good? Goldie Lookin Chain write funnier lines in their sleep.

They're "clever", sure, but only in the most venal sense. They're businessmen first, crunk-core MCs second. I wonder what DVDs 3OH!3 watch on the tour bus. They'd love us to believe that their favourite film is Jackass: The Movie. It's probably Wall Street.

3OH!3 ... Y-OH!-Y?