Love gave a modest but fluent demonstration of his turntablist talents while we watched his hands blurring on a big video screen. Like ice-skating, scratching has become a competitive sport, full of codes and arcane terminology, and Love's crew, the Scratch Perverts, are European champions.
Love demonstrated copy-catting, beat juggling, the drill, the crab and the combination scratch, carefully name-checking the DJs credited with each innovation. Renegade and Love scratched with dexterity and bravado but their short set was more about process than end result - this was a lecture theatre, not a club.
Schaefer works methodically, building up a soundscape from a small selection of vinyl. His "triphonic" turntable has three playing arms, so he can use one LP as three sound sources: music runs backwards, forwards, slowed down, speeded up and processed into unrecognisable abstraction.
The audience, thankfully, were prepared to learn rather than confirm their prejudices. You didn't have to buy into any aesthetic world view - DJ culture, sonic art, avant-garde experimentation or even that of co- sponsors The Wire magazine - to enjoy it.
For me, the musical highlights were provided by Jeck, who wrought a long, largely improvised piece from a handful of old discs. His trademark is the use of four-speed mono Dansette record players; this retro equipment gave his performance the grandeur and pathos of Harry H Corbett's in Steptoe & Son; the addition of a discontinued Casio sampler added a hallucinatory sheen.
Sometimes, after a long stretch of jumble, Jeck's combination of stuck- needle sounds eased into synchronisation, the annoying click of a scratched single mutating into a steady drumbeat. At other times, his repetitive fragments recalled Terry Riley and Steve Reich's Sixties experiments spiked with humour, as out of the sonic soup emerged Morricone's "Chi Mai", marimba jive, a crying baby and a gentle voice saying: "what do you think this baby wants?" The preponderance of off-kilter loops occasionally slackened tension, but the piece was held together by Jeck's sense of pace.
During the discussion, when the turntablists were asked what they listened to at home, Jeck replied: "Fifties Frank Sinatra - the albums with Nelson Riddle." "At what speed?" shouted a wag. "Oh, I listen on CD," said Jeck.