When Brooklyn duo Sleigh Bells first struck gold with unprocessed, hyperactive rock through 2010 album Treats, they sounded like nothing else around. Their debut was defined by its own sense of excess. Never had noise been delivered with as much unfiltered fun. At the time, Sleigh Bells seemed like a singular prospect.

Six years on and not a great deal has changed, in that sense. Vocalist Alexis Krauss and guitarist Derek Miller’s signature remains relatively untouched, even though they themselves have tweaked a winning formula over four albums, each more experimental than the last.

“I’m not gonna lie. I do think about it. I do think our sound is very distinct,” says Miller, shuffling in his seat. His argument isn’t arrogant, but he’s aware that it could be misinterpreted. “If someone can read this right now and go, ‘Well I’m gonna show this asshole’ and put together a riff with a giant kick drum, well…”

Sleigh Bells’ status as lone rangers in the frenzied, gung-ho pop stakes might not have changed, but everything else has. For a start, fourth album Jessica Rabbit is the first to be self-released via their own Torn Clean label (UK label Lucky Number Music hopped on board for a release on this side of the Atlantic). While the pair claim they’ve always had creative control, counting the pennies shifted how they view their output.

“In the past [with previous label Mom + Pop], we’d turn in the records, send them the masters, deliver videos when they were finished,” Miller states. “But I do think the fact that we self-released and everything is on us, the burden is on us,” says Krauss, from the Hackney apartment where they’re staying for a week. “Creatively we’ve always taken on those decisions but financially, a lot of things are on our backs now.” Miller agrees. “There’s now never a stage where you recoup it later. It’s out of our pocket, on the spot. I like that pressure though.”

Between 2013 LP Bitter Rivals and now, the duo were prompted with label offers, but none of these offered the kind of freedom they’d had in the past. “Mutual approval” is the term Krauss cites, motioning inverted commas. “That was what we ended up breaking away from.” Miller claims they “don’t respond well to parameters”, a neat summary for their musical style and overall outlook. “So this is the only way forward.”

It wasn’t like their trademark hard worn thin, but Jessica Rabbit feels like a refreshing cleanse of the palate. The record’s opening seconds go as you would expect, launching with Miller’s sawtooth guitars. But the rest is a revelation; a murkier, deeper exploration of noise. "I Know Not To Count On You" marries finger-picked acoustics with wild synths, while the berserk "Rule Number One" wouldn’t exist without Kanye West’s Yeezus, according to Miller. Throughout, Krauss commands a different world to the one she inhabited before, flicking a switch between subtle pop and all-out hysteria.

The way they express what it means to be in a band, you’d think Sleigh Bells were maniacally enthusiastic newcomers. They describe last night’s Tufnell Park Dome gig as their “favourite ever” London date. Krauss says that every show they play “literally takes my breath away,” adding: “My heart starts racing and I have to settle myself down so I can actually breathe and sing.”

Miller speaks about other artists’ music with as much respect as his own. A recent Kanye West gig “changed my life, without question,” he beams. “I left that show believing in myself more than I ever have. That’s the gift that show gave me. It gave me so much confidence. I walked out of it thinking, ‘I’m gonna do whatever it is I wanna do’.” And he extends this energy towards the band’s own mantra. “If someone walks out of your show feeling great about themselves. If you’re not trying to do that, then what the f**k are you trying to do? We’re trying to communicate to each other in a way that’s meaningful and inspiring so that life is less shitty.” It’s rare to find a group, four albums in, with the same intense energy they had when starting out.

Making a record “always feels like life and death, to me”, says Miller matter-of-factly. “Every moment for me is make or break. Every song, it’s like, ‘I have to feel like this is the best thing we’ve ever done or it’s gonna be a complete waste of time and I’m gonna feel like utter shit’. It’s actually even more intense. It’s almost troubling, how high the stakes always feel to me.” He agrees that Jessica Rabbit is a “critical moment”, not least because they’ve found a new means of expression. This was always the danger with Sleigh Bells, that the fizz of their early material might simmer out, enthusiasm for their game-changing slant dying in turn. Instead, they remain relatively peerless. Groups such as Death Grips and records like Yeezus share the same table-flipping, no limits ethos. But it’s remarkable just how few acts have emerged attempting to mimic or distort Krauss and Miller’s legacy.

With that in mind, they remain hugely in demand. They’ve been approached to write for big-name pop stars, and Miller recently had sessions with hip-hop giants Run the Jewels. But such is their belief in Sleigh Bells, the pair tend to keep the best material for themselves.

“Without fail, if it’s worth giving to somebody else, it would have to be something that’s good enough to send to Alexis,” Miller laughs. “So I’m always going to send it to her first. And there’s never been a time where she’s not like, ‘I have a really good idea for this.’” Krauss admits that she “would like to explore more of the pop songwriting aspect, down the line,” but she’s not keen on a playlist-ready collaborative track or “having a big radio song.”