Simon Shlomo Kahn knows how it feels to be on top of the world. For almost a decade, he was an award-winning, recording-breaking beatboxer setting new standards for his craft and astonishing audiences with his risk-taking, rule-breaking shows and blisteringly kinetic energy.

As Shlomo, he burst in to the mainstream collaborating with Bjork and working with famous fans from Damon Albarn, Lily Allen and Jarvis Cocker to Imogen Heap, Martha Wainwright and Rudimental. As the first ever World Looping Champion, he taught his friend Ed Sheeran some tricks. He was Artist in Residence at London’s Southbank Centre for years, played the main stages at Glastonbury more times than he remembers, won rave reviews for his autobiographical one-man shows and even had a feature film made about him.

But being on top requires a balancing act that becomes increasingly tricky to maintain. New heights always have to be reached, fresh goals have to be found, acclaim has to keep coming. By his mid-20s, Simon started to question what he was constantly striving for. His mantelpiece strained under the weight of awards that meant little to him. He would walk off stage to standing ovations and feel oddly empty inside.

His mental health was a mess.

Two years ago, he took a step back to work out what he wanted and that fast-spinning world he had been standing atop crumbled under his feet.

“The bubble I’d created just burst,” says the London-born musician, now back as solo artist SK Shlomo. “I’d always been incredibly driven. In early adulthood, I had impenetrable hubris – absolute belief that everything I hoped for would happen – which hugely contributed to my success, but ultimately was at the expense of my mental health.

“Beatboxing was relatively new and I saw an opportunity to take it in new directions and give it legitimacy. When that went to plan, I had to outdo myself, hit the next high. I was the first person to create a beatboxing choir, or a perform a beatbox concerto with an orchestra, but by the time it sold out I was already chasing my next achievement. The pressure I put on myself was unbearable.”

As the highs kept coming, the lows crept in. At first it was drink and drugs. Behind the friendly persona that audiences adored, Simon felt himself falling apart and sought help. It was, he knows now, a first fork in the road. He conquered some addictions – he is now proudly 10 years sober – but kept their cause at arms’ length.

Behind his reinvention lies a realisation – that throughout his 20s, he had resisted writing the solo album he desperately wanted to make for fear of failure. He’d had offers from record labels, but wriggled out of them when it came to making a record. Despite composing and producing for other artists, as well as for film and commercials, he’d been too insecure to expose his real self in his songs.

“Much of my entertainer persona was built out of insecurity,” he says. “I can admit now that it was a mask for my fear of just getting in the studio. All performers wear masks, but mine was holding me back from doing what I really wanted – solo recording.

“I had a mantra that became my excuse. I’d say that beatboxing was a live art form, that it wouldn’t make sense on an album. And the more innovative my shows became, the more I could tell myself that was true.”

In 2015, having played Glastonbury with Rudimental, and Wilderness with a 50-piece orchestra, Simon put beatboxing to one side, turned off his machines, sat at the piano and starting writing in his home studio. The catalyst was partly becoming a parent – or as he candidly puts it, ‘the realisation that I exist to do more than beatbox’. But it was also a drive to address demons that lurked in his past.

The first solo song that he wrote, the first that he’d ever truly opened up on, was the haunting, hypnotic The First Time, a multi-layered, richly-atmospheric recollection of losing his virginity.

“From the moment I made it, I knew it was more heartfelt than anything I’d ever written,” he says. “I’d been listening to lots of Caribou, Jamie xx, James Blake and older acts I love like Massive Attack. The plan was to make soulful electro, but I didn’t really believe I could sing well enough.”

For a year he visited a vocal coach to help unlearn what beatboxing had taught him.

“I had to stop doing some crazy shit with my tongue,” he laughs. “But when I relaxed, a key unlocked and my voice totally changed. In the past, I was always straining, trying to sing high and powerful. Suddenly, it was soft, low and gentle, which is how I speak. I realised it was easy to sound like myself.”

Last summer, Simon set himself a challenge – to write a song every day for a month. For the first five days, he delivered. Then he had what he calls a mental meltdown, culminating in a suicidal episode which led to six months in therapy. Diagnosed with PTSD, he was forced to confront his past.

“I had been terrified of an incident that happened to me aged four,” he explains. “It was always in my mind, but it was just too painful to look at. One night when I was four, after weeks of stomach aches, I remember being stuck sat at the top of the stairs, hugging my knees, paralysed by horrific pain in my belly. I couldn’t move, or breathe, or call for help. My next memory was of waking up in hospital after emergency surgery and having a giant scar across my belly.”

An intestinal condition that almost killed him was the cause, the only fragments of memories that remained were of the unbearable pain. Last year, for the first time in his life, Simon asked his parents to describe the incident that had overshadowed his early years and for which he had long blamed himself.

“Talking about it was a huge turning point,” he says. “I realised why I felt I had to be responsible to survive, why I had always pushed myself so hard to succeed. The relief was overwhelming.

“That’s when I realised what the album I was making was about. It’s called Surrender because that’s all the four year old me could do – let go and trust. It’s about stopping trying to control everything around you.”

Surrender’s first single is the sensual, slow-building Invisible, on which brutal lyrics blend with beautiful electronic sounds part inspired by Simon’s Middle Eastern heritage.

“My mother’s family are Iraqi immigrants and I grew up immersed in Arabic music,” he explains. “It’s a cultural identity I’ve included in stories in my shows before, but never in my songs. Invisible is about feeling something creeping in against your will and quietly destroying everything you have. It’s an emotional song that builds and builds and finally lets rip. To play it live is empowering. It feels like I’m taking my pain and making it my power.”

Under his new moniker SK Shlomo, Simon found himself taking a ‘dark pop’ direction.

“It took a while for me to accept that I am making pop,” he says. “But it’s not shiny, bubblegum pop. All of the songs have an edge, a deeper meaning.”

There’s Superhuman, a gorgeous, disorientating ode to addiction that describes the musician’s darkest moments and the clubby Stardust, a sparkling collision of chaos and calm that celebrates new beginnings. Half a dozen more songs are almost finished. The crowdfunded Surrender is slated for release early next year.

The album, written and produced by SK Shlomo, blends beatboxing with synths and samples, layered up to 100 times per track with vocals and harmonies.

“I will always beatbox, but now it’s the spice of my music, not the meat,” explains Simon. “I still find making beats by mouth easiest. I use software to manipulate the noises that I’ve made, the same way I do with samples, turning them into rhythms or drum machines.

“I call on all of my training – my background in jazz and orchestral music, my work with choirs and a cappella past, plus my Middle Eastern immigrant roots, which you can hear in the harmonies.”

Some of the new songs have been played live at small shows in recent months, but received their proper premiere at a launch at London’s Southbank in June, with a four-piece band and a 30-piece choir. For a musician who thrives on breaking the rules, it’s the closest Simon has come to a traditional set-up on stage.

“None of my achievements in music arrived the traditional way,” he says. “Appearing on Jools Holland at the start of my career was about it. I always strived to do everything differently, to create my own path.

“But I’ve realised that the biggest challenge for me is to stand up on stage and simply be myself. No clever machines, no fancy techniques, no persona. This is the real me, naked so to speak. It’s the scariest, most exciting thing I’ve ever tried.”