Rochdale's Sean Booth and Rob Brown have become leading practitioners of what has been tagged "intelligent dance music", a term synonymous with former ravers who have subsequently grown beards and started reading novels. Autechre loathe the tag; perhaps enough to develop a form of live performance which is, on the face of it, very silly.

The venue is freezing cold and everything is pitch black, including the stage, which results in the curious spectacle of people in darkness staring at people in darkness. It is almost a parody of the old cliche that electronic duos are nothing to look at - only a glimpse of movement suggests they are actually on stage.

Autechre are rather fond of in-jokes, and seem to be worryingly aware of the old Throbbing Gristle jape about locating a sonic frequency that will empty people's bowels. The sub-bass, that rumbles discreetly on their albums, is cranked up to levels so high that you expect reports of another earthquake.

Stomach contents stay where they are, but their biggest prank is to mess with people's heads, as their own music is scrambled and mashed-up beyond recognition. Vaguely danceable rhythms are suddenly destroyed by sonic screeches.

Some brave souls look po-faced as if this is something terribly important; others look baffled. One poor man is so disoriented that he walks into a door. When the duo start speeding everything up to comedy levels you start to wonder if this will be the first time "intelligent dance music" has given an entire audience black eyes. It seems less like a performance than a bizarre experiment in human behaviour.