Judging by early reactions to their forthcoming debut album, it seems very likely that Secret Machines will be big by the end of the year. In one respect, however, they are already massive. In a venue barely bigger than a wardrobe, their sound swells and bulges, like a giant in a too-tight suit. Waves of guitar and Fender Rhodes crash across the room. Drumbeats cannon off the walls. They threaten to shrug off the ceiling.

Even at this stage, Secret Machines have the aura of an event band. The three New York-based Texans make music for open spaces, where people can sit cross-legged or dance chaotically with their eyes closed. Never saying a word, they seem in a world of their own. Behind geometrical fringes, brothers Brandon and Benjamin Curtis hammer away at Rhodes and guitar respectively, while drummer Josh Garza is just a blur of hands and frizzy hair - the Muppets' Animal after a summer in Haight-Ashbury. You get the sense that even if the audience were to suddenly disappear Secret Machines would motor on, merrily oblivious.

Their most admirable quality, however, is their restraint. Inspired by the trance-rock tradition that runs from Pink Floyd to Can to My Bloody Valentine to Spiritualized, they could feasibly extend their circling mantras until long after the last tube has gone, but they are equally informed by the tight songcraft of the Beach Boys. Often a juddering thrum will mushroom into the kind of rapturous melody the Polyphonic Spree would give their harp-player for.

Nowhere Again resembles The Golden Path, the single the Flaming Lips recorded with the Chemical Brothers, as Brandon Curtis approximates Wayne Coyne's awed croak. Road Leads Where It's Lead, with its ominous cry of "blowing all the other kids away", achieves a kind of euphoric menace, like a looser-limbed Radiohead. Put Secret Machines underneath laser-lit festival skies and there'll be no stopping them.

· At the Mean Fiddler, London W1 (020-7434 9592), Thursday.