'Do you want to get tooled up while I make a pot of tea?" says Squarepusher, aka Tom Jenkinson. For a fan of his music, being in his studio is like peering into the kitchen of your favourite restaurant: you fear it will dispel the magic of the recipes. For 10 years, since he was 19, Jenkinson, has been swallowing sound - two-step, jazz, funk, contemporary classical, ear-bleeding noise - and spitting it out in a unique form of drum'n'bass excess. In person he's welcoming and relaxed, with a very attentive gaze. Not bad for a guy who hates being interviewed and has a reputation for being grumpy. But I'm not here to ask questions, at least not in that way.
Jenkinson has had to cope with a lot of questions about his next gig - a performance with the London Sinfonietta, as part of the Ether festival in London. It's a "world-colliding" project by the South Bank, with works by Steve Reich, Aphex Twin and John Cage. Not the usual setting for Squarepusher's "spunk jazz" and "drill'n'bass" - music that has inspired Andre 3000 from OutKast to hail Jenkinson as a bit of a genius.
Instead of a face-to-face interview, Jenkinson and I decide to have a jam. Why talk to Beckham when you can go out on the pitch with him? But before I arrive at his studio, trombone in tow, we strike up an email conversation. This is his preferred method of conducting interviews: it allows him to consider his answers and so avoid misrepresenting himself. He has a way of making himself disappear from the equation - like someone who has a powerful conviction that they have no conviction:
"From Tom: When it comes to the actual fact of how I make my music, I have nothing to say. Not because I am secretive, but because I cannot do the process justice by verbalising it. Whole days, weeks of my life have vanished making music. I have virtually no conscious recollection of it."
Up in the studio, there is no talk of how or what to play. "Thought we'd just see what happens," says Jenkinson, plugging his bass in. He's recently moved back to London and it's a tight fit in his bedroom studio.
There's always an odd moment just before you start an improvised piece of music. It's a kind of no- man's-land between the conversation stopping and the music starting. But Squarepusher's off, rattling round his bass, hitting it and playing the strings at the same time - doing drum'n'bass on one instrument. Most people see the trombone as the fat guy in the corner, but it has a few nifty tricks up its sleeve. I follow with bursts of very fast, short notes, a bit of drum'n'bone if you like - and probably sound like a typewriter falling down the stairs.
"From Tom: This is probably the only interview I have managed to complete in the same way I make my music. I started typing at 12am. A few moments ago I looked up it was 3am.
"The case of what attracts and repels in my music is simply not for me to worry about. True, you can sell a lot of units by manipulating popular cliches. Unfortunately, for me, that's not an option. I did actually try to make a 'housey-builder' piano track in 1994, as I was completely broke. But everybody said it was rubbish."
Back in the studio, I try something brassy and jazzy and he responds in such a refracted way that what I am blowing feels like a cliche. He has adopted the spirit of it, but mangled it. That's one of the best things about Squarepusher's music. Everything he touches gets watermarked in a way that's tough to counterfeit.
We trade like this for a while, throwing in bits of jazz, sound effects, cop show riffs. By this time I am shouting down the instrument. The strange thing is that, from inside the music, it doesn't feel so fast. You pedal slower but keep going at the same speed. I feel like a juggernaut heading for the eye of a needle.
"From Tom: To succesfully operate any machine, the mind has to replicate the machine internally. The operator absorbs the logic of the machine, and thoughts proceed in a way alien to 'normal' thinking. That is why great performers are fascinating to watch, because they no longer embody humanity - but rather the logic of an instrument or machine ..."
The beats have stopped in the studio. We are floating around in a little tune. It is like one of Jenkinson's melancholy numbers - Tommib, say, the song that accompanied Scarlett Johannson as she gazed at Tokyo in Lost in Translation. Now we're just playing the same note. Have we finished? Forty-five minutes has passed.
"Hello Monsieur. I'm sure some of my audience will find it a depressing moment when their favourite throat-lacerating, bass guitar-destroying maniac is invited into the soporific atmosphere of the Royal Festival Hall."
Jenkinson knows there is a cynical reading to the Sinfonietta gig: classical group collaborates with edgy musicians to harvest audiences and street cred. But any attempt to set-off musical camps does not impress him. "I hope my music could help temporarily transcend such preoccupations ... I simply see it as a gig that I can invite my grandmother to without her being suffocated on dry ice."
Outside the flat, Squarepusher says: "It's been a real pleasure." Somehow we start talking about out-of-date swear words we would like to bring back. He opts for "crud".
"From Tom: We have survived the onslaught of planetary extremes only to emerge into the suffocating uselessness of causes, ideas and hopes. That may seem disappointing, but that's the problem in according value to the results of actions, as opposed to simply enjoying taking part in them ... The number '0' will never be boring to me because in it I see the infinite, the string composed of the addition of all other numbers, stretching beyond sight in both directions."
· Squarepusher and the London Sinfonietta play the Royal Festival Hall, London SE1 (020-7960 4242), tomorrow, then tour.