It's no secret that LCD Soundsystem's frontman James Murphy has a sweet spot in his tastes: The moment when post-punk and disco were carrying on their clandestine affair, roughly 1979-1982. The records he loves most have aged better than most of the dance music that came before or after them, because what their creators cared most about was freshness of sound; they abjured synth presets, classic drum sounds, received-wisdom arrangements, overfamiliar ways of singing. It's a little odd, then, that so much of what LCD does best involves recapitulating the ideas of music recorded 25 years ago or more.

The best track on their iTunes-only A Bunch of Stuff EP-- six tracks, 49 minutes, all versions of songs from Sound of Silver-- doesn't sound much like LCD Soundsystem. That's because it isn't: It's a cover of "All My Friends" performed by Franz Ferdinand, and recast in a full-on dance-rock arrangement that keeps racheting into higher and higher gears. The Sound of Silver version hews closely to its sources (especially New Order's "Ceremony"); Franz Ferdinand's radically different arrangement gets around the question of quotation and paraphrase, leaving only a grand evocation of the post-punk chill. (John Cale's version of the same song, released at the same time in the UK, has shown up over here on yet another digital-only EP.) The other highlight is at the close of the EP: a galloping live-on-the-radio reprise of "Us v Them", played by LCD's spectacularly tight and forceful (and under-documented) onstage incarnation.

Between them, there's a quartet of remixes, none of which are quite as good as their Silver sources, but a couple of which are noteworthy anyway. The "c2 Remix Rev.3" of "Sound of Silver" is ambiguously labeled, but turns out to be a spacious, drone-based mix by Detroit techno master Carl Craig. And Soulwax's 10-minute remix of "Get Innocuous" is a jittery, slow-building jam that spotlights the analog sequencers and drum machines of Murphy's favorite era. (As an elbow to the ribs, it even quotes Kraftwerk's "Trans-Europe Express".)

LCD's love for that period continues on a Fabriclive mix CD credited to Murphy and the band's superhuman live drummer Pat Mahoney. The records in their crate (the mix is apparently all vinyl-based) aren't entirely from that sweet spot-- they drop in some ringers from Murphy and Tim Goldsworthy's DFA label (LCD's own "Hippie Priest Bum-Out" and Still Going's new "Still Going Theme"), as well as Daniel Wang's 1993 "Like Some Dream (I Can't Stop Dreaming)". Still, it mostly sticks to the sort of songs about desire and dancing you might have heard at a particularly cutting-edge club during Margaret Thatcher's first term. If they don't get in much of the underground rock that's the other half of their roots, they make up for it by beginning and ending with tracks from Love of Life Orchestra's 1980 album Extended Niceties-- David Byrne's rhythm guitar on "Beginning of the Heartbreak" sounds a bit like Al Doyle's on A Bunch of Stuff's version of "Us v Them", actually.

Technically, the Fabriclive mix is just fine, for those who care about such things: Reasonable if not totally perfect beat-matching, occasional tempo shifts handled by the convenient tactic of switching to an a cappella. A segue between G.Q.'s 1980 album track "Lies" and Mudd's 2004 "Adventures in Bricket Wood" is so smooth it just sounds like the bassist has switched to a different riff. But the point of this set isn't its precision as much as its heady overall flow and crate-digging-- virtually every track here is somewhere between "nice dollar-bin find" and "what the hell is that?" The closest Murphy and Mahoney come to a disco standard is a 90-second snatch of Was (Not Was)'s "Tell Me That I'm Dreaming", and they work in oddities like Jackson Jones' "I Feel Good Put Your Pants On" as if they were club classics. In the context of the mix, Punkin' Machine's "I Need You Tonight" sounds for all the world like a new DFA record; it turns out to be a Canadian obscurity from 1981. That, in fact, is Murphy and company's most curious accomplishment-- being the Pygmalions of art-disco. They haven't just returned to the aesthetic of a quarter-century ago: They've breathed enough life into it that it's become a contemporary aesthetic, too.