"The more uncomfortable you feel, that means I'm doing my job," snarls David Foster, AKA Huren, from behind a table of gear. I'm at OHM in Berlin. It's 4PM on a muggy Sunday in July. Outside the sky is threatening to split. Inside, the white-tiled space is lit an unsettling red. "I'm lucky I'm alive at 43, I forget more than you'll ever absorb," says Foster, wild-eyed. He's looming over the table and leering at the crowd one minute, crawling on his knees the next, as a barrage of pummelling beats detonate, showering us in shards of power electronics. "I wanna see this vessel expire…"

This is $CUMTRONIC$™, a venomous project Foster has described as "structured relapse therapy." It's his battle cry against the injustices of the modern world, fuelled by rage and personal torment. The set only lasts about 40 minutes, but Foster is bled dry by the end of it. As are we. It was barbed and intense but at times lighthearted. It was also one of the best live performances I've seen all year.

Along with Kareem (Patrick Stottrop) and Hecate (Rachael Kozak), Foster is part of Zhark Recordings. At OHM, Foster and Stottrop are commemorating 20 years of Zhark together with the label's current roster. These days Zhark is run by Stottrop out of Berlin, and it's experiencing a busy period in an otherwise patchy existence.

Kareem (Patrick Stottrop) in New York, 1996.

In June, the label released its first EP from Stärker, an ashen ambient techno record filled with dread. Last year, they put out a swollen industrial two-tracker from Manchester's Casual Violence and the first single in Huren's -MRTVI- series. Before that there was Stottrop's The Sky Is Gone But You Are Still Here. That one broke the label's seven-year period of inactivity with the kind of menacing yet rhythmically engrossing soundscapes that made Stottrop and his dark empire such a favourite. To Zhark fans, the comeback seemed like it was never going to happen.

"It could have been the end," says Stottrop. We're talking about Run, the last Kareem record that came out before the label entered its lengthy "hibernation" phase. Alongside three steely techno cuts, the EP included a searing remix of "Distorted Prose" by the New Jersey hip-hop outfit Dälek. Hip-hop is Stottrop's other passion, and is part of the reason Zhark wound down in 2007. Around the same time, Stottrop released Irreparable Damage, a collaboration with Shadow Huntaz on Ramadan, a Zhark sub-label dedicated to "Kafkaesque hip-hop breaks." Productions for abstract German rapper Audio88 soon followed. "I would be gone for a couple of years working on a hip-hop thing," says Stottrop, "which I could easily fall back into."

Huren (David Foster) in New York, 1996.

Zhark began in New York in the mid-'90s, when Stottrop left Berlin to study journalism at NYU. There he met Rachael Kozak, a Detroit native who studied painting at the School Of Visual Arts in Manhattan. Stottrop had a laptop, a novelty back then; Kozak was already working with the first version of Cubase and had programming experience from her project with John Ryan as Citizens Of Shade. Stottrop was more of a DJ but they bought some kit and started experimenting. After a year or so of "just playing around" they had their first demo, The Payback.

"The first demo tape I ever gave to anyone was Autechre," recalls Kozak. "I remember talking to one of them on the phone and they said, 'This is really too dark for us.' I thought of the label's name, as I love sharks, it's as simple as that. Turns out in German it sounds like the word for 'coffin' so it suited us perfectly. I went on to make the logo and we ordered 800 records. I will never forget someone asking me around that time, 'So who is doing your distribution?' And I said, 'What distribution?'"

"Whenever I would go on vacation, I would take records in my suitcase," Stottrop tells me. There was no plan behind the label. Kozak was 19 at the time and working at Strange? Records on the Lower East Side. The first order came from Daniel Bell in Detroit. Stottrop and Kozak did a second release together, and then parted ways. "Patrick wanted to go more into the dance floor techno vein and I wanted to make more noise and experiment with breaks and also play with some vocals," says Kozak. "We parted on good terms, to some degree."

Stottrop returned to Berlin in '97. Kozak eventually moved to London after completing a digital multimedia course at Vancouver Film School. But neither were quite willing to let Zhark go. Kozak started Zhark London, later renamed Zhark International. Stottrop continued with Zhark Berlin, or just Zhark. "I think it was kind of stupid," admits Stottrop. "It's true, why didn't we just say, 'Hey, you know, let's do something else.'"

Kozak's first act by herself was to curate Zhark Compilation, released in 1998, which featured some of her productions as Hecate (and a track as Lynn Powderhorn) alongside material sourced from friends who shared her caustic vision. This included Alec Empire and Khan, as well as David Foster, whom she had met while still living in Detroit. Teste was Foster's first project—"Just a teenage angst experience of having no connection to anything at all around you," he tells me. It was short-lived. The group, which also included Himadri Gosh and Søren Browning, released just three records on the Plus 8 sub-label Probe Records, before they disbanded and Foster began working as Huren.

His first three EPs for Zhark all came from the same two DAT tapes, sent to Stottrop through the post. "David set up the new style and the new Zhark approach without us even talking," reflects Stottrop. The sheer brutality of tracks like "Tinseltown" reset the label's standards. In 1999, Stottrop released Black September, the label's toughest Kareem productions yet. The untitled A-side comes over you like waves of nausea. It features simmering layers of noise, all set to a frogmarch by one almighty kick drum. It's evil but also rhythmic, almost boiling over in an excruciating climax before returning to the pit from whence it came.

These days there's a healthy scene for noisy, experimental and industrial music, made up of labels like Repitch, Downwards, Blackest Ever Black, Contort and Perc Trax. But back in the late '90s Zhark was an underdog fighting its corner. "German distributors actually really struggled with the harder sound at that time," recalls Stottrop. "Because it was all about minimal… I tried to keep it a bit more accessible—dark, but accessible. Then with number seven it became distorted, crazy. A lot more intensive and a lot more extreme.

"When I look back on those records, they're just chronicles of a bad personal life I had at the time," says Foster. "It was just complete frustration… I mean, I did actually like techno at the time, but I just didn't think it was intense enough or as abstract as I wanted." But the releases weren't always pedal-to-the-metal. Foster's Boxed Meat Revolution, for example, wove shadowy breaks with stinging rhythmic noise; Kareem's Mikoyan EP united deep techno with acerbic IDM and left-field hip-hop or downtempo. There were the occasional dark ambient outings or "illbient" moments too—an echo, perhaps, of Stottrop's years in New York.

After spending the best part of four years shaping Zhark, in 2001 Foster and Stottrop stepped aside to allow some new names to appear, and disappear almost as quickly. Harsh was a friend of Stottrop's. The others, including Nathan Siter (an architect based in Finland) and French analogue artist Le Talium, were found from demos or from chance meetings at gigs. But, with the exception of Nathan Siter, most of these Zhark members have long since dropped out of contact.

Meanwhile, Kozak was flitting between London, Switzerland and Berlin. As well as performing and releasing as Hecate, she was managing an all-female electronic label, The Homewrecker Foundation. She mentions her first Hecate album, The Magick Of Female Ejaculation, as the moment her solo project took off.

Kareem and Hecate.

Early records from Venetian Snares (Salt) and Christoph De Babalon (Rise Above This) boosted the Zhark International brand during the millennial years, as the breakcore scene started snowballing. Kozak says she was taking Zhark in a direction influenced by horror soundtracks and the occult, as well as black metal and "the most current of hard-hitting electronics. I did my best to always release only the best and darkest of all of my artists... In fact, that is the only way you could be released on Zhark."

2005's infamous Abomination Of Desolation tour was a peak time for Kozak and the label. She recalls "getting paid some great fees, playing at the craziest shows and venues, and not giving a fuck about anything except what time we needed to get to the other city to do it all again." Around 2006, things began slowing down for Zhark International, as they did for Stottrop, Foster and Zhark in Berlin.

Ordet was Foster's last pre-hibernation EP for Zhark before, like Stottrop, he, too, become preoccupied with other things. "I just felt so disillusioned through my experience," he admits. "And somehow I knew how to play drums. I had some hometown friends that were on the same page as me, in terms of an industry standpoint. That was the most success I'd ever seen, riding on their coattails." Foster is referring to Junior Boys and the years he spent touring with the group as their live drummer, between 2005 and 2009.

These days Foster is perhaps the most active he's ever been. Since moving to Berlin over a year ago, he's linked up with Orphx's Richard Oddie to form Ontario Hospital, or O/H for short. Last year they released their first EP together, Future Ready, through Opal Tapes. Musically, it was headier rhythmic noise fused with Foster's distinct brand of punk-meets-industrial spoken-word bile. Part EBM, part power electronics, definitely retroactive but also plugged into what's happening right now, O/H is a significant new string to Foster's bow.

In 2014, Foster and Søren Browning reformed Teste, making their first appearance together at a Grounded Theory event at Stattbad in Berlin. Edit Select reissued The Wipe / Ascend and began the Rewipes series, a trio of EPs that saw Rrose, Dino Sabatini, Claudio PRC, Steve Bicknell, Mike Parker and Edit Select all have a go at remixing that definitive Teste track. This year Huren released a six-track cassette on AMOK Tapes and a fresh collaboration with Stottrop for Austrian label Noiztank.

Despite the recent productivity and apparent success, feelings of doubt hang over Foster like a dark cloud. "I'm just treating it like this could be the last show I ever play [as Huren]," he says of his set at OHM. "It's always on the verge of collapse." I ask if this extends to more than just Huren. "True," Stottrop says. "And anyway, it's a miracle that we are still actually doing it."

Stottrop is positive about Zhark's endurance; Foster is less so. His main concern is that it's all just part of a cyclical fad. "Might be better to leave it in that era," he says, referencing Zhark's heyday. "It's only going to be retranslated by the perspectivism of now, and it's not the same shit. That stuff was a certain way because of how it worked at the time."

It's part of a bigger personal anxiety for Foster. "I feel like, shit, there's all this attention on what I've been doing, and now I'm not part of a youth culture anymore." Back in the Ontario days, a very real physical detachment was intrinsic to Foster's music. He refers to Canada back then as "a complete disconnect," and he experienced "no impact at all" there from his early Zhark efforts, which were mainly selling in Europe, chiefly Germany and France. "Part of me wonders while being here in Berlin that maybe I have to leave again," he says. "'Cause coming here has affected my production."

Tresor, Berlin in the '90s.

In the past, Stottrop felt disconnection through being sidelined by the music that was more popular in Berlin. He uses old Zhark showcases at Tresor as an example: "It was always a struggle keeping people on the floor, the music was too hard," he tells me. "People complained." Too hard for Tresor? "Yeah, but our approach was different," says Stottrop. "It was the beginning of Drumcode," explains Foster. "A specific era in techno, just that banging techno sound. And we never fitted in with that."

Foster takes a sense of pride in clearing a dance floor. He says it happened recently at Suicide Circus in Berlin. "But I thought that was good," he says. "It's like, I still got it." The opposite was true when I saw him at OHM. Outside I met a couple who had driven from Holland just to attend the gig. Like me, they were not disappointed. Foster himself may feel outmoded, but his music certainly isn't—it's just as fiery, just as relevant as ever.

Stottrop has also returned to the gig circuit in recent years, performing at Berghain, Contort and Tresor. Unlike Foster, who's used a variety of setups in his time, Stottrop has been performing live with software since 2001, when the first version of Ableton came out. He used to collect records and DJ with vinyl but sold his entire collection to play his own material instead. He's now getting back into standard DJing, though he's very particular about what goes into a Kareem set.

Stottrop closes OHM playing purely records from the Zhark back catalogue, and once again it's among the best things I've heard all year. It's about 11PM now, as dark outside as it is inside. The dance floor is a hive of activity. I'm surrounded by grinning faces and balled fists punching the air in time to the techno beats ricocheting off the walls like bullets. Then, just as we enter the most intense portion of the mix, things ebb away into broken hip-hop before being nosily built back up again. The 100-odd people here tonight are revelling in Zhark's incomparable past as well as its possible future.