Look no further than Rob Ellis, aka Pinch, and Sam Shackleton to provide a welcome antidote to the growing glut of glimmering, sexless bass music currently munching up the underground. Since dubstep's particle-accelerated velocity started to slow around eighteen months ago, various different aspects of the sound have fractured off into their own different niches, and it's been harder to find the sense of unified forward development that bound everything together until early 2010. Instead several different factions have emerged. Near the surface is the chart-bothering, big-room pop-dance coming from the likes of Skream, Benga and Katy B, as well as Skrillex and Nero's spotty moshstep (the former of whom, thankfully, still has yet to invade the UK quite so conclusively as he has done the US). Then there are people like the Hessle Audio crew, Brackles and Braiden, who used funky's rhythmic leverage to pry open the genre's basic structure, slowing it down and leaving it vulnerable to outside influences (particularly house music). And then there are those sticking to the established dubstep 'template', such as it is - 140bpm, bass-heavy mind/body music - and either honing it to deadly efficiency (Mala and his Deep Medi label; Youngsta's DJ sets) or using it as a base from which to explore the genre's limits (Bristolians like Kahn and Zhou, and many residents of Pinch's Tectonic label).

Ellis himself falls into the latter category. His 2007 Underwater Dancehall album was a bona fide classic, one of the finest long players dubstep has yet produced, and since then he's been drawing great hunks of influence from dub, house and techno into deeply individual, meditative club tracks. Shackleton, meanwhile, is one of the genre's great outliers. Like Burial, his sound is more sui generis than strictly 'of' dubstep, but when he first started releasing music though his and Appleblim's seminal Skull Disco label it was deeply in thrall to the FWD>> sound of the time. He's spoken in interviews of experiencing the shocking minimalism and physical punch of early Digital Mystikz productions (Loefah's devastating 'Horrorshow'; the skip/thud drive of Mala's 'Neverland') on Plastic People's pitch-dark dancefloor. And although stirred with influence from the post-punk lineage of Cabaret Voltaire, PiL and Throbbing Gristle, most of his music has remained at a similar - and therefore mix compatible - tempo to dubstep proper. Over the last few years his already distinct sound, drawing together rhythmic influences from non-Western music and hot, dusty sub-bass like desert wind, has become increasingly idiosyncratic. By the time of last year's live sets and blinding fabric.55 mix, it had been transformed into spiraling death disco for a new age of austerity.

It's likely because his sound is so distinctive that Shackleton's is the most audible voice on this formidable collaboration, entitled, simply enough, Pinch & Shackleton (with two names this revered, why bother elaborating?). His beats don't so much play as chatter, like dried leaves in the wind or the brittle, sinister cloc of bone against bone, and their searching, very organic discourse is one of the album's defining features. Other Shackletonian traits are here in abundance too: disembodied, paranoid thought-loops, sometimes wordless, sometimes less so ('Burning Blood's "And you'll have the most selfish and greedy life... 'nd greedy-eedy life... eedy life..."); sub-bass tuned so such a deep vibration that it rattles crockery on the other side of the room; the rolling inevitability of techno.

But what makes this such a fascinating and important record is that it's far from being a straight up Shackleton album. Ellis' presence in the music here is subtle but vital - he exercises a great deal of restraint, holding the music poised distant from the manic intensity of Shack's recent output. For the most part Pinch & Shackleton lacks the quivering mid-range drones that whip across the latter's music. Instead, their collaborative efforts set feather-light high end - rolling congas, whistling melodies - across a droning raft of low end, evocative of a landscape that's flat from horizon to horizon. At times, too, it's closely attuned to dub's love of studio trickery. 'Levitation' and 'Torn & Submerged' are both more spacious than anything either producer has made before - 'Torn…' in particular is a huge canyon violently ripped into the album's otherwise rather uniform topography.

Pinch & Shackleton doesn't really fit into any particular category with ease. That said, while it might be the most 'dubstep' thing Shackleton has put his name to, and the least 'dubstep' thing Ellis has ever done, it remains fixed around the genre's typical speed. This serves to emphasise just how powerful 140bpm can be as a tempo: slightly too fast for the body's rhythms to follow, it contains a kink, mid-bar (the eponymous 'half step') that drags dancers into a spaced out skank, encouraging them to move at two different speeds at once. The effect is druggy and hypnotic, in a crowd-control sort of way. Ellis and Shackleton are both masters of that dynamic, and their interplay here lays bare the essential issue with much of this year's straight up 'bass music'. If not done carefully, dropping dubstep-rooted rhythms to 130bpm and below runs the risk of losing their compulsive sense of motion; many of the broken house rhythms currently infecting UK dancefloors have lost a great deal of their parent genre's tensile energy.

Most striking of all, though, is the compositional sophistication on display here. It's something that, if you weren't listening carefully, could quite easily go unnoticed. It wasn't until I spent an hour DJing with the album's tracks that it became clear that they operate in a constant state of flux. Each track moves through several different iterations so subtly and skillfully it's easy for the transitions to pass a listener by. Take opener 'Cracks In The Pleasuredome', which creaks into life like battered old machinery, dragging itself upright through three minutes of ominous greyscale drone before slumping into a lilting, raga-like groove. Or the aptly titled 'Rooms Within A Room', a veritable Russian doll of a track where each new room offers new delights: triumphant dub reggae brass; stammering polyrhythms not far from Cut Hands' viciously brilliant Afro Noise project; the mournful strains of a submerged choir; crackling steppers' techno.

Never let it be said that dance music has to be simple. Pinch & Shackleton is a love letter to club music's many possibilities, and to the brooding power still locked tight within dubstep's framework. And it's magical, from start to finish.