The 2009 release of Kode9's dancefloor bomb 'Black Sun' marked the middle of a turning point for Hyperdub, the moment at which it appeared to take on a life entirely of its own and wrestle control from the hands that guided its early development. The previous eighteen months had found the label wracked by blasts of corrosive, overly synthetic melody, sonic representations of the mutagenic agents that were infecting the scene at the time. In some cases these resulted in Marvel Comics-style superhuman transformation (the bulging circuitry of Ikonika's 'Please' bursting free, Hulk-esque, from dubstep's percussive limitations; loneliness borne of post-human isolation in Darkstar's 'Squeeze My Lime'); in others total meltdown of the host organism's cellular support systems (Zomby's self-titled EP, where dance music conventions weren't so much stretched as dissolved entirely, allowing tissue fluid to ooze thickly from the resulting mess).

But even at their most extreme, these new entities remained essentially locked to the core 140(ish)bpm structure that defined dubstep. In contrast, 'Black Sun' broke links with the genre entirely, retaining the toxic waste glow but slowing the tempo and aligning with the nascent sounds of UK funky. The label's subsequent output began to follow suit, more snapshots from Kode9's energy-intense, genre-blurring sets pressed in black wax at closer to 128bpm: mutant funky from Cooly G, Scratcha DVA and more recently Funkystepz, catchy kwaito variations from LV & Okmalumkoolkat, lo-fi house from Ikonika. Hyperdub's championing of these underground sounds both influenced and predicted the ongoing developments of the last two years', which have seen the tempo of UK urban music drop further into a bubbling stew of 'what-u-call-it' house/grime/two-step hybrids – everything from the party grime aesthetic of Night Slugs and Funkystepz to Hessle Audio's ultra-percussive reductions.

So even taken apart from the narrative concept that apparently lies behind it, it seems appropriate that Kode9 and the Spaceape's long-awaited second record is also called Black Sun. Not only is the music itself a logical sonic extrapolation, a stretching of the original track's intent across an entire album's length, it also represents a break from the past and a conscious means of distancing the duo's new music from the chrome-plated chill of their 2006 debut Memories Of The Future. Which isn't, to these ears at least, as necessary an action as its makers might think: that record was (and still is) often lazily lumped in as a textbook example of 'a dubstep album', when in fact even at the time of its release it was as distinct from its contemporaries as Burial's self-titled album. Several leagues from the dub warmth of DMZ and Pinch, the dancefloor bump of Benga and D1 or Vex'd abrasive tech-futurism, Kode9's beats were stark and alien, as if drained of all their bodily warmth. Alongside Spaceape's downtuned, stream of consciousness drawl and the album's sci-fi artwork, they formed uneasy meditations on an all-too-real modern dystopia. Rather than lumping them into an already fragmenting scene, Memories Of The Future set the duo apart as a unique entity unto themselves.

Black Sun continues that trend; it's so far removed from any current fads sweeping the UK's electronic and urban music scenes that it's tempting to imagine it was created in a vacuum. In real life, Kode9's role as Hyperdub A&R and DJ must have exerted a great deal of influence, but self-conscious genre-exercise or simple synthesis this is not. Nor is it an album at all geared towards dancefloors, though many tracks on here are razor sharp examples of how to move a club crowd. But it is representative of the current disparate state of UK borne bass music, whether through design or accident (the latter seems more likely) – it's a record which establishes a voice then flits between a number of different structures without remaining in thrall to any one of them. While embracing that mongrel spirit at times results in Black Sun feeling slightly disjointed, it also results in moments where its nervous energy appears to spill from the speakers.

Opener 'Black Smoke' begins the album with one such moment: beginning slowly with thick, glassy bleeps, it appears to accelerate exponentially as successive layers of skittering percussion stack onto one another before collapsing into one of Kode9's trademark sustained synthlines. As an opening statement it's an appropriate one, accurately laying out the sonic formula that defines the rest of the album – urgent, insectoid beats, dissonant blasts of radioactive synth, chanted, mantra-like vocals. It reaches its pinnacale with the breakneck death rattle of 'Bullet Against Bone' and the muted effervescence of 'Promises', the former bringing to mind the duo's 'Abeng' from last year's excellent Scientist Launches Dubstep Into Outer Space album. The album's similar sound palette throughout does result in the feeling of a constant stream, lacking many standout moments in favour of a whole hour's worth of cohesive listening. While this works well at home, there are fewer tracks here that would cause the hyper-kinetic effect on a dancefloor that the original 'Black Sun' still does.

To fit with the increased pace and intensity of Kode9's beats, Spaceape's delivery has subtly shifted since the first album, perhaps as a result of the duo's increasingly energetic live performances. Rather than rolling, rhythmic spoken word, it approaches conventional MCing, playing tag with a lopsided two-step beat on 'Neon Red Sign' and driving forward with relentless intensity on 'Bullet Against Bone'. And though cryptic as ever his lyrical themes show a newfound personal directness, eschewing the bleak word games of his earlier performances. Rather than taking on the role of the world-weary prophet, as on Memories Of The Future, on Black Sun Spaceape is a wild-eyed street preacher, shouting himself hoarse on a packed city corner.

Appropriately given Spaceape's persona here, Black Sun is apparently held together by an overarching story, a sort of Ballardian sci-fi noir where the world's population is bathed in radiation from our sun's sickly death throes. As a standalone listen, however, it would be difficult to figure out any such concept through the lyrics themselves; non-press editions of the album come with artwork which explains it in full. That's not at all detrimental to the album on the whole, though 'reading along' might well enhance the experience. On the other hand, sonically it's evocative of stereotypical images of a post-apocalyptic earth: the semi-aquatic synths of 'Black Sun (Partial Eclipse Version)' (the album's midway instrumental, reloading the original with all the edges melted away) recall The Drowned World, and beatless closer 'Kyron' – a collaboration with Flying Lotus – marks the point at which the sun's destructive power finally overwhelms our planet's population.

As a complete entity, Black Sun marks the complete departure of the duo from the spaces orbiting dubstep. Future releases will presumably be judged on this benchmark, rather than on the imagined connection between Kode9's toxic beats and the thick halfstep still emerging from certain regions of the underground. But it also does the same for Hyperdub itself, marking a further node in the evolutionary tree of one of the UK's most consistently interesting labels. The ongoing shifts in the duo's music are mirrored in (or perhaps mirror) the label's changing sound and aesthetic. It's hard not to suspect that their next record will be as different from Black Sun as this one is from their Memories Of The Future, but that's of little consequence right now, when their current output is this strong.