Playgroup is U.K.-based electro maven Trevor Jackson; in addition to making Romper Room punk-funk party bombs like 2002's Playgroup (notable for including cameos from both Edwyn Collins and Shinehead), Jackson runs Output Recordings, a superhip English label that's home to chilly post-rock acts like Fridge, and Colder. Jackson is also an ace remixer, a fact this cleverly titled two-CD roundup handily verifies. His thing, like most mutant-disco types, is the kind of bass-anchored groove that sounds elastic and hard at the same time. Reproduction doesn't show off Jackson's facility with a sampler or a sequencer, as many brand-name remix discs do; it's more about extending a track's vibe just beyond the breaking point. So he jacks up the smash-the-state snarl in Radio 4's "Dance to the Underground" and supplies Chicks on Speed with the wiry funk beat they're after in their cover of Tom Tom Club's "Wordy Rappinghood." In his dub of "I Need Your Love," by New York fashion plates The Rapture, Jackson cools out the band's black-light throb until singer Luke Jenner sounds like he's lost in space and can't find his way out.