A startling entrance is vital to a good rock concert. Bands have tried everything: pyrotechnics, paragliding, clambering out of giant rotating lemons. At their debut UK concert, however, the Polyphonic Spree, Dallas's self-styled "choral symphonic pop band", create a stir without wires or fireworks. They simply troop through the audience in a line.
What is diverting is the sheer number of people involved - 25 clamber on stage - and the fact that all of them are wearing matching white robes. They look less like a rock band than a religious cult's musical wing; lead vocalist Tim DeLaughter leaps around the stage with his hands outstretched like a gospel preacher, while the rest of the band perform wreathed in blissful smiles. They point at members of the audience and wave cheerily. One man plays the French horn while performing Pete Townshend-style scissor kicks - a sight that would impress the most jaded crowd.
Their antics would be slightly unsettling if their music were not so warm-hearted and uplifting. A band including brass, woodwind, strings, three keyboard players, kettle drums and an 11-piece choir can't help but sound thunderous and anthemic, but the Polyphonic Spree match their epic sound to a richly original vein of songwriting. Their songs lie somewhere between the Beach Boys' abandoned psychedelic epic Smile, the hippy musical Hair and the Muppet Show. Their lyrics have the direct simplicity of children's songs - "Hey! It's the sun!" offers one track, "and it makes me shine!" - while the music swells euphorically. It sounds wonderful.
Midway through their set, the band's power cuts out. After a few moments of embarrassed silence, DeLaughter elects to sing unamplified. Encouraged by the audience, the rest of the band join in. The effect is spellbinding. Suddenly the amplifiers crackle into life again, just in time for the song's immense crescendo. It's an accident that confirms that the Polyphonic Spree are a truly unique band.
· The Polyphonic Spree play a free show at the Ballroom Stage of the Festival Hall, London SE1, on Saturday. Details: 020-7960 4242.
