ROCK / A weird posse parps at pews

ANYONE passing through Islington early on Thursday evening might have noticed eerie noises emanating from the Union Chapel. Above the shimmer of tiny handbells and the muted clatter of percussive objects, rise the gentle honk and parp of trumpet and alto saxophones played with almost supernatural delicacy. The Art Ensemble of Chicago have come to town, and if you think they sound remarkable, you should see how they look.

There's mercurial post-modern trumpet-talent Lester Bowie in his habitual lab-coat, with a trim grey flat-top and distinguished little beard, showing no ill-effects from his recent brush with wicked uncle David on Black Tie White Noise. The two saxophonists, Roscoe Mitchell and Joseph Jarman, are dressed contrastingly: one as hip-hop kid, with backwards baseball cap and sad eyes, the other - like bass player Malachi Favors - in tribal garb, complete with warpaint. Rounding off the ensemble is drummer Famoudu Don Moye, in spangly gold raiment.

The church setting adds another layer of weirdness - here is the world's most revered futurist jazz posse playing in front of a pulpit. The crowd, sitting in pews with plastic beer glasses perched awkwardly in front of them, seems slightly bewildered - no one knows why they didn't have to kill to get a ticket. Later, some will complain that the show 'wasn't avant-garde enough'.

The idea of 'playing tribute to the Chicago blues tradition' is not just about the artistic vanguard going back to traditional roots, it's about showing how two sets of roots have always been tangled. These are working musicians, after all, not porcelain figures. Keyboard queen Amina Claudine Myers, one of the blues musicians who joins the Art Ensemble after half an hour to effect a 'unique union of two vital strands in Chicago's great musical heritage', played with Mitchell and Bowie to great effect a quarter of a century ago.

The guitarist Herb Walker rustles his frets and the whole lot of them - innovators and traditionalists together - lurch into a strange unreconstructed blues thing. Chicago Beau and his pub- rock harmonica are the only clouds on the horizon. Malachi Favors jigs about in a delightfully unhinged fashion and two fine young horn players - Frank Lacy and James Carter - alternate between sudden blasts of virtuousity and giving the crowd fierce looks which say, 'What have you lot done to deserve this?'

Across town at the Hammersmith Apollo, fans of Chaka Khan are asking themselves the same question. Chaka - another child of the Windy City - demands more respect than her insulting bit-part in a Whitney Houston video suggests she is currently getting. Her audience - a harmonious assemblage of contrasting skin-tones and sexualities - woof their approval; not just of particular phrases as she sings them, but individual syllables.

A great night seems in prospect. Unfortunately, the woman beneath the crimped orange haystack has other plans. It's not that Chaka can't - when she does open her mouth to sing, the voice is as stunning as ever - but that she won't. This woman will do anything to distract herself from the mundane reality of giving a performance. She plays with her hair, fiddles with her boots, bawls out her soundman. Worse still, she covers her tracks by encouraging her band to indulge in interminable Kenny G-style instrumental interludes.

You have to have real star quality to get away with this kind of behaviour, and Chaka invests her hour or so of supper club jazz standards with majestic hauteur. 'I hate to think of anybody going home disappointed,' she says, blithely spurning shouted requests for 'I'm Every Woman', 'but, well, that's life.'

Erstwhile Replacement Paul Westerberg handles an illustrious past with better grace. He's got a new band now, but is touched rather than irritated by the fervour which his old songs inspire. At a packed Borderline, popular pressure forces him to join the dots in his young backing trio's repertoire. He calls out the chords to 'Swinging Party' (one of several affecting ballads which made The Replacements' songbook the essential Eighties bar- band primer) as he goes along, and still manages to give the words feeling - 'If being afraid is a crime, we hang side by side.'

If there is any room in your heart for raucous, wistful, guitar- soaked Americana, Westerberg - at his best - is the man to fill it. When not at his best, as unfortunately on his first official solo album, 14 Songs (Sire), he builds soppy statues from Keith Richards' cast-offs. Tonight, though, he is great. The sound bounces chunkily off the back wall and he seems to be uplifted by the enthusiasm of his new sidemen.

Last time The Replacements played here they seemed fed up with not making it. A certain obduracy, not to mention too close an acquaintance with the liquid refreshments where they played, stopped them attaining more than a sort of celebrity ideal of regular guyness. Matt Dillon and Wynona Ryder loved to drop their name, but they never sold many records. With a new band behind him, Westerberg's songs sound fresher than ever. 'Here Comes a Regular' is what Cheers would have sounded like if it was a musical.

If Charles Bronson and Burt Reynolds could have a son, he'd grow up looking like John Prine. That alone does not explain the familiarity of this distinguished but rarely seen singer-songwriter's face. First sight of him also calls to mind an older Bob Carolgees. At the Grand, Prine plays on his own; swatting his guitar with such vigour that it has to be taken away for reconstructive surgery, and rasping out songs from a three-decade career which, with the success of his most recent album, The Missing Years (This Way Up), has finally shrugged off the 'new Bob Dylan' tag.

Tonight, he lets his songs do the talking. Usually with country, less is more, but Prine's roughness of voice and the simplicity of his chord structures cry out for a nice bit of pedal-steel guitar and some background harmonies. His best songs, 'Angel of Montgomery' and 'Speed of the Sound of Loneliness', sound better sung by Bonnie Raitt or Nanci Griffith. The crowd don't think so, though, howling along to 'Illegal Smile' with glee. But he loses them at the end: 'Well done, son of a gun, hotdog bun, Attilla the Hun, My sister in law . . . is a nun.'

(Photograph omitted)