Oumou Sangare, Barbican

That world-music fans should demand the finest sound on CD, yet happily put up with bog-standard amplification at concerts, is one of the great mysteries of our time. This week, the Malian songbird Oumou Sangare provided a case in point. As her bewitching new compilation on the World Circuit label reveals, she uses her voice like a jazz singer, and plays against her acoustic band with exquisite musical refinement. OK, we knew we wouldn't get that quality of sound when she made her triumphal return to the Barbican, but did it really have to be quite so bad?

The one-string fiddle came over like a sax, and the gentle kamalengoni lute - with a big mike dropped into its innards - had a harsh and strident sound; only the percussion came across as it should, while Oumou herself had to belt it out in order to be heard. As so often on such occasions, earplugs actually allowed one to hear the individual instruments more clearly, by cutting out the worst of the high-frequency din.

The best way to view this concert was as a reunion of friends, and in that respect - from the moment Oumou sailed regally into view - it was a triumph. How many people there spoke French, she wanted to know: to her delight. So she gave a running French commentary on her modestly moralising songs - about respecting women, caring for orphans, not loafing around when you're young - and delivered them with support from her barefoot singers.

There were some seductive grooves, and some sweet musical moments, notably when Magic Malik, looking like a Petit Prince in his pink-check suit, descanted over her voice with his flute. Oumou is a generous performer, bringing forward each musician for his slice of the limelight, and giving the audience all she has got.

What a contrast this made with a performance the previous night in a Clerkenwell church: assisted by discreet percussion on frame and goblet-drum, Ahmed Mukhtar - a former pupil of the Iraqi oud-master Munir Bashir - gave us his musical heritage in undiluted form. Bashir's maqam-based style traced its lineage back to Iraq's golden age, when Baghdad was the musical capital of the civilised world. Mukhtar's style is in the same tradition, but his speciality lies in drawing out the correspondences between his instrument and the cognate Spanish guitar. There were times when his chordal playing sounded almost like flamenco, but his rhythms and delicately flattened intervals were quintessentially of the Middle East.

Mukhtar, forced to flee Iraq to evade Saddam's long arm, now lives and teaches in London. During a question-and-answer session, he observed: "The sadness and the deep feeling you may hear in my music is part of Iraqi culture." That rang true, in every note he played.