Karlheinz Stockhausen, Billingsgate Market, London

The pew-like rows would have been absurd for such freewheeling electronic music were it not that Stockhausen, in his lucid introductory remarks, spoke of front and back as though he always had a standard concert-hall set-up in mind. Both works were for pre-recorded tape, with the composer adjusting levels from a desk in the middle of the audience.

Kontakte, the one from 1960, came as a shock. Obviously, the sounds are rooted in their period. The pre-digital tools would have been hard to work, the months of editing reel-to-reel tapes inconceivable. Yet the music being projected into the venue was gripping. It flows, swoops and surprises in total, playful confidence. Kontakte evolves seamlessly from start to finish like a dramatic poem. The materials may resemble natural and industrial sounds, but they move with their own rhythm and form.

Even in the second-half piece, an electronics-only excerpt from his week-long opera Licht, everything is prerecorded. Oktophonie, coming 30 years after Kontakte, uses eight sound sources to the earlier work's four. Yet, for all the greater resources, the big difference in Oktophonie was aesthetic. It has the composer's fingerprints of drifting sounds, brief rapid movement, and a concentration most fierce when the music seems to be calmest. But it is ruled by the basic musical element of pitch.

Events unfold around a series of long-held drones, in deep, often radiant timbres, which create a strong sense of harmonic structure. There's something Wagnerian about the scale of this mainly slow music, lasting well over an hour. For all its roots in the past, this epic puts traditional notions of modernism way behind it. The standing ovation suggested it has come to speak universally.