Say what you like about Kurt Wagner, the man has guts. It's only two years since he gave up his job as a floor-sander in order to concentrate on a career as songwriter and lead singer for Nashville based alt. country heroes Lambchop.

The band's breakthrough album Nixon was an irresistible blend of Curtis Mayfield-style soul and pedal-steel laden pop. Resisting the temptation to repeat the formula, Wagner wrote and recorded Is a Woman, a painfully slow collection of downbeat ruminations on such topics as death, divorce and attempted suicide. Now he has hit the road with a live show that is not only weighted heavily in favour of the new material, but which couches the bouncier Nixon songs in the same muted and minimal arrangements.

The band's latest line-up features 12 musicians as well as Wagner. There are two drummers, assorted guitarists, a pedal steel player, a pianist and an electronics boffin. It's a recipe for one almighty racket - yet the songs undulate gently, at an almost impossibly low volume. Wagner scratches away at his acoustic guitar like a man who has been told to keep it down by the person lying beside him in bed. His smoky, charismatic voice often descends to a whisper, while around him the softly cascading piano competes not at all with the drummers' shuffling brushwork and the eerie electronic ambience.

The band perform the new album almost in its entirety, sticking very close to the sound and arrangements of the record. The new songs are all based around one or two simple motifs, but the chord progressions and tunes are so languorously elongated that every verse seems like a symphony. There is movement here, but it is the slow, almost imperceptible movement of icebergs melting. The sound is impossibly deep and luxurious, the atmosphere veering between icy majesty and smouldering understated passion.

The audience is mostly appreciative, although there are one or two dissenting voices. "Play some old stuff, your new stuff's shit," someone shouts in anger during a between-song lull. Wagner presses on regardless, and if anything the music becomes even more quietly intense.

Finally, after an hour and a half, the band relent and slip in a couple of Nixon songs, but by then the evening is practically over. Leaving the auditorium feels like walking out of a cocoon.

Lambchop play the Royal Albert Hall, London, tonight, then tour. Box office: 020-7589 8212.