Philip Glass wrote and toured Music With Changing Parts in 1970. This, the first European performance since, was presented in conjunction with Tate Modern's Open Systems exhibition, and aptly so; the work is about sound rather than music.

A kind of manifesto of minimalism, it begins with burbling figuration from a single synthesizer, the player's hands mirroring each other. The rest of its unbroken 80-minute span is built from blocks of this, played on unspecified amplified instruments, incorporating shifts of rhythmic emphasis and very slight harmonic variation. Players can pick out and reinforce whatever notes emerge as overtones from the melee.

It was a test of stamina for the 12 members of Icebreaker. The three keyboard players, working partly in relay, would drum the figuration on their knees when not playing, as if afraid their fingers would seize up. But the precariously balanced rhythmic drive was sustained tirelessly by the group.

It was clear, too, that a live performance was the only way to experience the work. In the small space of the Almeida, the interacting noises generated intriguing effects: it could seem as though somebody close by was humming along, or that certain bass notes were coming from the back. We occasionally heard a trumpet that wasn't actually there. With the fast figuration blaring out from the saxophones and flutes, a strong bass presence and fuller harmonies, the minutes towards the end built into a carnival whirl.

But was all this ever truly original? For all its studied New York cool, this kind of work has a lot in common with good old English bell-ringing. Still, considering that Glass has recently seemed content just to churn out mind-numbing mood music, it was good to find, in this particular piece, something more than the sum of those changing parts.