Beyond Stadium Rock: The Story of STEREO, the Electronic Duo Born from Haloo Helsinki!

When massive success brings an arena-filling rock band to a temporary halt, what do its principal songwriters do? For Leo Hakanen and Jere Marttila—the creative guitar-slinging forces behind Finland’s premier pop-rock powerhouse, Haloo Helsinki!—the answer wasn’t to take a quiet vacation. Instead, they dove headfirst into synthesizers, heavy bass drops, and electronic dance music (EDM), giving birth to STEREO.

Though initially conceived as a high-energy side project during Haloo Helsinki!’s 2018–2019 hiatus, STEREO quickly carved out its own distinct identity, redefining contemporary Finnish pop and electronic production through high-profile collaborations and an infectious, club-ready sound.

The Genesis of STEREO

Haloo Helsinki! had spent over a decade dominating Finnish radio charts, selling out massive arenas, and reshaping the country’s mainstream music landscape. By 2018, the band announced they were taking a well-deserved break.

For Hakanen and Marttila, music-making is a constant state of being. Rather than stepping away from the studio entirely, they turned their attention toward a genre they had long admired from the sidelines: electronic dance music. Channeling their knack for massive hooks and melodic earworms into a digital framework, they formed STEREO.

The project allowed them to experiment outside the boundaries of traditional rock instrumentation, exploring the vast possibilities of digital audio workstations, club beats, and modern pop production.

A Star-Studded Collaborative Vision

What set STEREO apart from a standard producer-duo vanity project was its unique approach to vocals. Instead of anchoring the songs to a single permanent singer, Hakanen and Marttila operated as masterminds and curators, inviting a rolling roster of prominent Finnish artists to front their tracks.

This collaborative strategy created a dynamic playground where different musical worlds collided. The project’s 2019 self-titled album and surrounding singles featured an impressive cross-section of Finland’s music elite, bridging generations and genres:

• Samu Haber (formerly of Sunrise Avenue) lent his unmistakable raspy vocals to “Sä saat mut palasiksi”.
• Michael Monroe (the legendary frontman of Hanoi Rocks) brought his trademark punk-rock swagger to “Woo Woo”.
• Rising rap and pop sensations like Etta (“Vuosien päästä”), Sini Yasemin, and Aste infused the tracks with fresh, urban energy.

Signature Sound and Notable Tracks

STEREO’s music is characterized by its glossy, high-definition production value. Hakanen and Marttila famously collaborated with world-class mixing engineers—such as Miles Walker, renowned for his work with Beyoncé, Bruno Mars, and Rihanna—ensuring that their electronic beats could rival international standards.

• “Vuosien päästä” (feat. Etta): Serving as one of their breakout singles, this track combined melancholic, deeply emotional lyricism with a driving, festival-ready EDM rhythm.
• “74”: A sleek, instrumental-heavy electronic cut that highlighted the duo’s meticulous production skills.
• “Bonnie & Clyde” (feat. Ida Paul & Kalle Lindroth): A seamless fusion of acoustic-pop storytelling and electronic grandeur.

A Fleeting, Impactful Chapter

As Haloo Helsinki! eventually returned to active duty, STEREO’s primary chapter slowed down, remaining largely anchored to that vibrant 2018–2019 window. However, the project left an indelible mark on the artists and their fans.

STEREO proved that Hakanen and Marttila were not just guitarists of a successful rock band, but versatile, forward-thinking producers capable of shifting the needle in Finnish electronic music. It stands as a masterclass in how a creative hiatus can be weaponized into something entirely fresh, proving that great songwriters can bend any genre to their will.