Zero 7, Brixton Academy, London

Hark back to 2001 and Zero 7's debut album, Simple Things, is playing in the background. Inoffensive and treacly, it replaced Air's Moon Safari as the soundtrack for dinner parties, upmarket boutiques and comedown sessions. Simple Things shifted 800,000 copies, took Zero 7 into the charts and was nominated for a Mercury.

Three years on and the British press - who fawned over Henry Binns and Sam Hardaker's earlier output - are sneering at the follow-up When It Falls. Accused of replicating the bland formula, When It Falls has also suffered from being released in the shadow of Air's charmingly experimental third album, Talkie Walkie. Portentously, Air recently struggled in Brixton's hulking rock venue. Tonight doesn't bode well for Zero 7. It seems unlikely that their unobtrusive background music will transform into an exhilarating live show.

Aware that moshing isn't on the cards, Zero 7 have made efforts to liven things up. It's not just Binns and Hardaker twiddling the knobs on stage; tonight they are a crew of 10, including five capable vocalists.

The set starts promisingly with a punchy rendition of "Warm Sound", which benefits from live guitar, drums, flute and Mozez's honeyed soul vocals. Molten lava projected on a big screen above the stage enhances the fuzzy glow. But it's statuesque Tina Dico who captivates us with her tumbling blonde locks as she gently wriggles her hips for "Home". More ballsy is long-term collaborator Sia. Her powerful nasal twang warrants comparison with Dolly Parton, especially in the country-tinged "Somersault".

"Passing By" introduces Sophie Barker, resplendent in a fuchsia trilby and black strapless dress. Despite her brave attempts, the delicate track works better on record - in Brixton it plods tediously.

Things get worse when Zero 7 meander into jazz-funk solos, encouraging their musicians to push their chests forward like neurotic chickens. For "When It Falls", the keyboard player is projected on to the screen so we can see exactly how crazy he's getting. It's the old tracks "Waiting Line", "Destiny" and "I Have Seen" which provoke the most rapturous reception.

Zero 7 are technically astute; they honed their production skills working in RAK Studios for stars such as Robert Plant and the Pet Shop Boys. Tonight's gig benefits from their obsessive attention to detail: the sound is brilliant, production's slick and both albums are regurgitated proficiently. But their relentless niceness drags, and it wasn't a wise choice to finish with the downbeat instrumental "Morning Song". Although some people leave, Zero 7 return for two painful encores. Ultimately they have trouble holding the boozy Saturday night crowd's attention. As one fan comments: "They need to crank it up a bit." Or stick to chill-out festivals.