Clearly those early goals were surpassed some time ago.

"We've been extremely lucky," says Clarke, his softly spoken voice at odds with the banshee screech he unleashes as Deafheaven's frontman.

"I think we've always tried to be honest in our music, and we try and be honest people. And I think our music can be very vulnerable at times, and very emotional to the point of heart on sleeve. Maybe people connect with that."

Ordinary Corrupt Human Love is a wildly kaleidoscopic affair, moving from tranquil, atmospheric piano passages to searing extreme metal while navigating myriad other musical waters.

Three of its songs weigh in at more than 10 minutes, with Canary Yellow tipping the scales at 12.

Deafheaven are not, in other words, the sort of band you'd expect to find a mainstream audience in 2019.

Yet when they return to Australia this month for their third tour, they're one of the headliners of Wollongong's Farmer & The Owl festival alongside acts such as Beach House and Hockey Dad.

The roots of the band stretch back to the schoolyard, when Clarke and McCoy bonded over Clarke's Slayer shirt.

"We became really fast friends," says the singer. "To be fair, I had no friends. I was kind of desperate!"

The two are the sole original members of the five-piece.

"We've been best friends for an extremely long time," Clarke says. "In this whole music adventure that we've decided to do, it's nice to have someone you can trust and bounce ideas off."

There have been bumps in the road – around the time of 2015's New Bermuda, inner-band tensions and a fondness for the rock 'n' roll trappings started to take a toll, leading to some personal "adjustments" at the completion of that album's touring cycle.

"Becoming an adult," chuckles Clarke. "Growing up a little. I think we're a very hard-working band, but we were treating everything too lightly at times and I think the hanging out and partying became [too] important and got away from us a little bit.

"I turned 29 and was like, I don't know if I want to be going into my thirties being 'party guy'. I'd had a very good run at it, and it'd been a lot of fun. But I wanted to see what else there was."

The newfound focus meant coffee was the stimulant of choice while writing Ordinary Corrupt Human Love, accompanied by a newfound positivity and a willingness to experiment.

Risks were taken, nowhere more so than on album opener You Without End, a contemplative piece built around soothing piano chords and the narration of actress Nadia Kury.

"When you're in a positive mood and someone suggests something, you're automatically more open to it," Clarke says.

The band's calendar is booked solid through to October, after which they'll start to focus on album number five.

It's fair to say Clarke won't be collecting a pay cheque from a grocery store any time soon.