One makes predictions about world music's mainstream popularity at one's peril, but it is hard not to be cheered by the audience gathered for Mali's celebrated blues-rock duo. There are doughty campaigners who can remember when it was all Andy Kershaw round here - middle-aged men doing the legendary Middle-Aged White Guy Dancing To African Music Dance - but now there are teenagers and hipsters as well. Perhaps it's the Damon Albarn effect, Amadou and Mariam being among those who have enjoyed his tireless patronage.

The core elements are fabulous: Mariam's voice, at its most vulnerable and affecting on Sabali; the cyclical riffs of Artistya and Magossa, sounding somehow inventive, fresh and oddly familiar at the same time. On Masiteladi, Amadou peels off spectacular guitar solos, fluid, gutsy and effortless. On stage, the duo are insouciantly cool: both blind, they stand virtually motionless, huddled together, while their tough, insanely funky music bounces off the walls. During romantic numbers, Mariam strokes the arm of her husband, whose between-song announcements are in French. The audience invariably respond with: "Yeeeeah!"

You can't fault their enthusiasm, but it's hard not to feel this is an approach doomed to end in grief, like the holiday-maker who ends up ordering a plate of lightly battered testicles because he won't admit he doesn't understand the waiter. And so it proves. Introducing one of the duo's politically inclined numbers, Amadou asks: "Est-ce que vous aimez les démagogues?" By the sound of it, they love les démagogues as much as they loved la danse, which he asked if they liked earlier. Amadou looks baffled. "Non," he mutters. "C'est pas bon." Then he goes back to his guitar, a language everyone understands perfectly.