The past few years have been both a bounty and something of an endurance test for Autechre fans. This past May, the duo of Rob Brown and Sean Booth released elseq 1-5, over four hours of new material. It earned comparisons to dumping off a bag of clothes at a second hand store and a Netflix show binge. That followed on the heels of last year’s AE_LIVE, which was over nine hours of live shows and 2013’s Exai, which ran for two hours (though still under the length of a modern superhero film). It sounds daunting—and yes, what the duo conjures up sounds daunting—as Autechre is shorthand for a type of difficult strain of electronic music once deemed “intelligent dance music.” There’s a good chance the word “algorithm” will be used when writing about their music, and despite their longevity, they remain at the vanguard, the Cecil Taylors of their field.

But for all that impenetrability, there's a lifelong friendship and dialogue that takes place between the two, regardless of the fact they now live in separate cities, building and swapping MAX patches from a distance. It’s a dialogue begun back in the late ‘80s, when they were electro-obsessed teens coming up in Manchester, swapping ideas and tracks on cassette tapes, jamming on analog synths and drum machines in their flats. It’s a dialogue that you can parse on their earliest albums, Incunabula and Amber, finally reissued on vinyl after they’ve changed hands online for three-digit sums. That complex and private language is evident from the start, situating Brown and Booth as the Poto and Cabengo of techno.

“Eggshell,” from their 1993 debut Incunabula, subtly reworks “The Egg,” a track from the epochal Artificial Intelligence comp that forever saddled them with the “intelligent dance music” tag . The Incunabula track locates a purgatory between the graffiti-friendly snare and hi-hats and disarmingly gorgeous, slow-moving synth line that evolves almost without notice behind the beat. The landscapes they evoke can seem post-industrial and dystopian, but the chord progression of “Kalpol Introl” still feels melancholic and definitely human. And while its approximately 75-minute length is unwarranted—the acid squelches of “Windwind” exhaust with their 11-minute runtime—there are both time-stamped presets as well as plenty of clues as to their evolution embedded in the album.

An early highlight, “Bike,” finds Autechre at their most songful, the bolts-on-concrete sounds of the 808s giving way to a beautiful ambient passage before that metallic beat returns. Even odder is “Basscadet,” a fan-favorite hit of sorts back in 1994. Built from what sounds like a hand drum tattoo and featuring a cheeky vocal sample saying “I don’t have any idea ‘bout what’s going on,” it features the abrasive electronic tones and scoured-metal aesthetic that would soon become the keystone to their future work.

Next year’s Amber might most closely resemble Aphex Twin’s Selected Ambient Works 85-92, but even then it shows them subtly begin to slide away from their techno roots. Some of their most ambient tracks are here, though it also finds them favoring darker, more industrial timbres that earned those early Cabaret Voltaire comparisons. It’s still disarming to see them use real words like “Glitch” and “Montreal” rather than the semantic jumble that would soon define their tracks. “Foil” builds with a beat that sounds like a whip against the titular material, the turbid washes decidedly more malicious than on their debut. The synth melodies of “Slip” haven’t aged very well, and the sharper aspects of “Glitch” and “Piezo” feel dulled and gentle in hindsight, knowing just what nasty and brutish sounds they would soon wring out of their gear.

What makes Amber fascinating to revisit decades on is to hear vestigial organs and sonic cul-de-sacs that Autechre would bin almost immediately after. Brown would look back and deem these melodic bits “cheesy” but if anything, it proves that at one point the duo was human after all. “Silverside” might be Autechre’s most haunted five minutes, even if the surge of orchestral soundtrack strings and distorted voice are two tricks that we’d never hear again. “Nine” might be the closest they ever got to the placid sounds of new age while “Further,” with its slow heaving minor key swells are as emotive as anything Autechre ever released. The flickering lullaby melody and spare pads of “Yulquen” reveal a soft, contemplative side that few could even identify as an Autechre track.

With 1995’s Tri Repetae, Autechre obliterated all that they—and most of their Warp roster mates—had done before. Rather than cut away vestigial parts, they scoured off all flesh and “cheesy” bits entirely, trash-compacted their hard drives and went full cyborg instead. While Aphex Twin used a dentist drill-high frequency to wheeze atop his single “Ventolin” earlier that year, Autechre made it their entire aesthetic, reconfiguring each component of their productions with that same level of sonic intensity. From the deep, sawing sinewave and rockslide of low tones that open “Dael” to the metallic thrums and chilling hiss of closer “Rsdio,” Tri Repetae served as Autechre’s superhero origin story, revealing a monstrous new power while also obliterating any trace of their previous selves. Rather than be able to trace the twisted metal of Tri Repetae to old Detroit techno singles and Mantronik sides, the lineage goes directly to Merzbow’s white-knuckle noise and the hammered metal of Einstürzende Neubauten. They’d push into more experimental and complex music for the next twenty years and never quite be as gentle or linear as those first two efforts.

The pewter sleeve bereft of any markings, the images of metal shafts and casings suggest that the humans behind Autechre were replaced not with robots but rather old radiators instead. Since then, experimental and dance artists alike—be they on labels like PAN, Tri Angle or Editions Mego—have absorbed certain aspects of Autechre’s sound. Whether you go for Oneohtrix Point Never, Arca, Holly Herndon, Russell Haswell, or Powell, they inhabit a world that Autechre helped make conceivable, so that even the cold metallic tones of their third album have somehow warmed with time. The bass growl that lurches forth on “Clipper” now feels triumphant rather than menacing, the whinnying frequencies of “Rotar” slowly tease out a melodic line. The spaceship vibrations of “Eutow” bears a low-rider beat at its center and the factory clatter of “Gnit” still reveals something quirky behind all the machinations. Revisiting Tri Repetae twenty-one years later is like returning to a planet previously filled with sulfuric acid clouds, volcanoes and liquid mercury pools. A hostile, post-human sound at the time of its release, it’s now startling to find residents living and thriving there.