Call and response: I say 'soul' and you think of what? A world where everything is smooth, all honey and gold, hushed lushness and midnight love? Is that your soul music: a sonorous, velvety voice expressing sexual ecstasy, unending pleasure, love-as-wonderful-addiction ("can't get enough of your love, babe"). Or does 'soul' conjure experiences, personal or political? A luxurious agony, tells of haunted nights and miserable mornings, shadowed by grief, heartbreak and loss. These are things we call 'soul music'. But another kind has to exist because the soul is, as any sinister Southern preacher will tell you, a troubled and wicked thing, full of sound and fury, led astray by demonic desires. The lives of the great soul men are riots of angst, addiction and sexual turmoil (think of James Brown, Marvin Gaye and Bobby Womack). What does a damned soul sound like?

Clams Casino's Instrumentals 2 is an astonishing combination: the longing and heartbreak of soul music staggering into a defaced, delirious kind of hip-hop. It's a soul music hollowed, with its regal delirium turning dark. Everything is wasted. Now, this is the weird thing: soul music is never instrumental because people think electronic equipment doesn't have a soul, and that soul can only be broadcast by the voice, but it's running through this mixtape, sinful, sorrowful and sad.

The absence of A$AP Rocky and Lil' B's voices means you can hear its luscious gloom in full glory and there's no obvious sense of loss, or spaces longing to be inhabited, holding their breath, like you find on some instrumental collections. But a special thrill is removed, too, that comes from the glorious juxtaposition of these eerie, smoky soundscapes with those voices howling about drugs, cash and rough sex. It's A$AP Rocky's numb and nimble rhymes that transform the black-eyed, brain-damaged lurch of 'Bass' into a magical spell. But there are still voices, buried alive in thick, delicious noise or slowed down to a hallucinatory growl: soul voices bruised purple. They come straight from the work of DJ Screw who, as theorist and DJ Jace Clayton put it, "dislocates body from voice" making "baritone rappers sound demonic... and female singers melt into androgyny". Purple is the DJ Screw colour. Through a bizarre hip-hop ritual of transubstantiation, purple drank (the opiate mixture of cough syrup and Sprite Screw regularly ingested and which stopped his heart) has become representative of the man and his method of aural disorientation.

This is the A$AP crew's way of getting wasted but it also points towards a rich and strange noise. 'Screwed', or slowed down, sound becomes spooky and sick with lust. Among the feast of riches he left for our consumption ('Grabbin' Grain' is wonderful, his molestation of 'In the Air Tonight' is a treat) there's a version of Teddy Pendergrass' 'Love T.K.O'. The tune is untouched until a heartbroken tumble into the syrup at the end, cavernous drums falling down stairs and vocals going s-l-o-w. Just like DJ Screw, Clams Casino is drugging commercial music and corrupting its soul, its phantom essence. A T.K.O is the effect of any opiate (a blank and gorgeous sense of heaviness), and it's the mood of Clams Casino's mixtapes, and the state they put you in. You're incapacitated, you don't know what's hit you.

This is the huge sound William Blake described in his visionary work The Marriage of Heaven and Hell, the rumble that comes as "hungry clouds swag on the deep". And if 'swag' has become a magic word and a kind of virus, then watch the clouds, too, which are about to take all kinds of shapes. 'Cloud rap' is what you're apparently meant to call this stuff, because it's hip-hop turned woozy, permanently strung out and sky-high. This is the glorious sound of music fucked up on heavy narcotics, barely able to keep its eyes open, drifting off in the middle of a... oh, shit, what's happened? Imagine the noise of the "ten million pounds of sludge" the Pixies sang about melting and exploding: that's what Clams Casino sounds like.

And listen to this, from David Foster Wallace's enormous novel of addiction and altered states Infinite Jest, where a drug addict lies in hospital, drifting towards his death. "He seemed to sort of sleep. He fever-dreamed of dark writhing storm clouds... screaming down on the beach". That's the sound of Clams Casino, too: feverish, hallucinatory and dark. It has the same woozy rush to it that you hear on My Bloody Valentine's Loveless and shares its fascination with glittering textures and drifting voices. I remember being hypnotised by the kaleidoscopic coda to 'Only Shallow' during a night of devilish activity and feeding my head into a speaker. Instrumentals 2 makes me want to do it again. Brian Eno called My Bloody Valentine "the vaguest music ever to be a hit" and this is what's so exciting about Clams Casino's music, too, its delicious vagueness that instantly conjures and induces a strange state, a 'sort of sleep' inhabited by slow motion ghosts. 'Vagueness' doesn't mean something undeveloped or opaque in this case, but a mood that's supremely seductive but unable to be spelled out - an unnameable allure.

Another presence is ringing in my dreaming ears and lurking behind all this material about clouds and 'cloud rap'. cLOUDDEAD sounded like hip-hop recorded in a vast lunar wasteland, heavy with echo and sumptuous sadness. Bizarre and oblique in a captivating way, cLOUDDEAD have the same effect as Clams Casino. The obvious difference is that cLOUDDEAD's first album features lyrics about "taking up space in a residence of stars". It sounds like the poetry of John Ashbery read by a gang of weird children (I would like, incidentally, to fully encourage an album in this vein, produced by David Lynch or Prince). But 'I Promise Never to Get Paint on My Glasses Again' makes the similarity clear. The same dreamy feeling surrounds everything, a sensation of 'sinking deeper into a vat of honey glaze', as cLOUDDEAD called it elsewhere.

Now, eleven years later, this strange and wonderful music is the perfect sound for hip-hop hooked on serious sensory derangement. That this isn't otherworldly, underground music but the sound of money-hungry hip hop keeping it (un)real is cause for manic celebration. I think I'm dreaming. Somewhere the Devil is stroking Clams Casino's soul.