"Excuse us if we're a little grumpy," says Tommy Hamilton—who, for the record, couldn't be further from it. His partner, Keith Tucker, certainly looks wearied, but is soldiering on regardless. It's September and the Detroit natives have their first Berghain show to prepare for. There's a slight catch, however. Their equipment has gone missing.

It's been a trying time for the pair best known as Aux 88. Two weeks ago they were in Croatia for Dimensions Festival. Billed for the Detroit-flavoured closing party on the RA stage, they were one of the many victims of the apocalyptic thunderstorm. They were actually set up at the time the skies opened, but they didn't get to play. Now, following a series of transatlantic misfortunes, they've landed in Berlin without their luggage. "But it's OK, it'll work itself out," says Tucker. "We're very versatile," says Hamilton. "We're pretty much equipped for any occasion."

It's the kind of cool response you'd expect from musicians with their experience. Hamilton and Tucker have been performing live together—on and off—for the best part of 30 years, first as RX-7 and then Sight Beyond Sight, before exploring the many nuances of "bass heavy techno" as Aux 88. They officially formed the group in 1993, going on to release the archetypal "My A.U.X. Mind" soon after. The track would be performed later that evening along with other stone-cold classics such as "Direct Drive," "Electro Techno" and "I Need To Freak." Not that tonight is a nostalgic showcase. They've cued up plenty of Black Tokyo and Mad Scientist material as well, guises the duo have been focusing on in recent years.

Aux 88

The Berghain tech crew have miraculously managed to put together a setup that Hamilton and Tucker can work with. The pair has spent the last two days on an airplane, but they are meticulous with their sound-check. As Tucker later tells me: "When we get down to making music, we get serious." They take to the stage and let loose the first of their Black Tokyo weapons, "Music Is Your Medicine," released on Tucker's own Puzzlebox Records, the official outlet for much of their music these days, in March this year. A guttural, grumbling synth line tears through the Funktion One system. My feet are vibrating. Then the sensual voice of Samara starts to purr through the haze.

It's probably the most pop-like track they've produced to date (this one will definitely get stuck in your head), albeit set to the sort of harder, darker style of techno they've always tended towards. Minor fluctuations aside, it's a formula that has remained consistent, even if the lineup of the group itself has not. Tucker left for a spell in 1995 to concentrate on his solo work as Optic Nerve and DJ K-1, leaving Hamilton to produce their sophomore album, Xeo-Genetic, on his own. Will "BJ" Smith of Posatronix was also a member for several years.

You'd think after a musical partnership temporarily disbands there would be some lasting effect on the relationship. But judging from the pair today, they're as strong as ever. In their maturity they've come to realise their individual strengths and roles within the group. Hamilton, for example, is the "tech head," says Tucker. "If I need to learn something new, I can ask him. And he masters all our music, too. Like, everything." They no longer meet up in the studio, preferring instead to pass things back and forth online, and letting natural competitiveness fuel their creativity.

This process has become the basis for their work as Black Tokyo, a collaboration with two female singers and musicians from Japan, Erika and Ice Truck. "We've never been in the studio together," says Hamilton. "That's kind of the way we planned it and it worked out really good," says Tucker. "That makes everybody have a hand in it." Despite recruiting the girls through a Facebook ad, on meeting in person the connection was instantaneous. "They were like our sisters. We just clicked," says Tucker. They first performed together at fabric back in 2010, coinciding with the launch of their debut album, Aux 88 Presents Black Tokyo. Though it was the project's first record, tracks had been been appearing in Aux 88 sets for six or so years.

The brainchild of Hamilton, Black Tokyo was conceived as a means of breaking away from the electro tag that had started to form around the group. Described simply as a fusion of Detroit and Japan, in tracks like "Reel To Real," "Shadow Dancing" and the lovely "Soul Of Black," it's an axis that sounds subtle and almost symbiotic. Over a trio of follow-up EPs, they've continued to refine the project in ever more lush and house-facing tones. They may have mellowed a little lately, but the ghosts of the Mad Scientist album and original Aux 88 toughness are never too far away.

Even though Black Tokyo has been brewing for some time, Hamilton and Tucker have been guarded about releasing information—or music, for that matter. It's the Detroit in them, they say. "We like to make people guess," says Tucker. "That's what keeps your name, keeps people interested, because you don't always give them exactly what they want all the time." And it's working. Black Tokyo appears to have pulled them out of their electro niche to play venues like fabric and prominent European festivals. It seems like they're tapping into that wider audience they've always aspired to, earning the sort of respect these chameleonic musicians deserve. But they're still refusing to rush into anything. "We like to let things marinate for a while," says Tucker, "because people are constantly finding out about the music."

The other key element of the duo's success has been live performance. Aux 88 are in their element on stage. Back when they were re-enacting Cybotron and Kraftwerk hits as RX-7, the only thing they looped was their drum machine. The rest was furiously and lovingly tapped out on keys. And today little has changed. They may have traded in the gear and dancers for laptops, but an Aux 88 show is as energetic and entertaining as ever. "The songs will never sound exactly the same," says Tucker. "The way we do our songs, everything is on a time limit. We know how long the songs are, so from around the three-minute mark we are doing whatever we want to do. That's been our secret. You wont realise what it is at first, and then suddenly..."

"We didn't even think to tell you what we've been working on," Tucker says just before the next sound-check calls time on what has been a very long 48 hours for the pair. "One reason why we haven't been putting out music specifically is because we've been working on a documentary. And I don't even know why I forgot that." Almost a year in the making, it's a film shot, produced and directed by Aux 88, about Aux 88. Feeling like they've never quite gotten their story across in the hands of others, they've decided to go ahead and tell it themselves. Due out next summer, we might gain a better understanding of who Aux 88 are, but something tells me they're going to keep us guessing for years to come.