"Oh, they're like Keane!" squeals a friend. Outrageous as the comparison seems, the dusky melancholy of the Furries' opening number does, at a stretch, evoke those wishy-washy balladeers. Only for a moment, though - then a pair of trumpeters in monks' habits chirp a salutation that sounds like kick-off at a New Orleans funeral, as lava lamp squiggles drift across a big screen.

Singer Gruff Rhys, who will later don a space helmet, is mumbling a ditty called Demons. In the audience, jaws are slackening as the music turns into a synapse-frying drone. All of this happens in the first five minutes, and there's two hours to go.

Having proved that they barely inhabit the same universe as Keane, the Welsh psychedelic quintet spend the first half of the evening (the show is divided into segments featuring hypnotic slowies and rockers, with an interval to check that your brain is still ticking over) transfixing the crowd. It's impressive to watch entire rows of seated adults rock forward from the waist until their heads graze their knees.

The band are plugging a best-of called Songbook, which compiles the woolliest moments of their six previous albums. Much of what's played during the first half, though, seems to be chosen at whim: a blissful lullaby sung in Welsh; the painfully beautiful Turning Tide, with a bit of classical flavour added by violin-playing monks.

Part two goes with a jolt, starting with the deceptively titled Slow Life. Rhys winches on his helmet, waves a sort of light sabre, and the volume is ratcheted up. Rings Around the World and Golden Retriever exemplify the Celtic trait of wresting melody out of guitar rock. There's a large mirror behind the band, giving the impression of a world beyond - just the sort of magical place that produces songs like the cascading God! Show Me Magic, and the dozen or so that follow. May their magic remain potent.