Browning cardboard egg trays line the wall of the underground rehearsal room at Alliance Française. Soundproofed from the outside world, a group of guys goof around on an electronic piano, a drum set, guitars and microphones. A tall, muscular fella in a white vest, blue, bleached skinny jeans and size 12 Converse sneakers is singing a naughty reworked version of a popular tune.

His band mates burst into laughter as the melodious punchline leaks out of the speakers. This is Sauti Sol at rest. Away from the bright lights and screaming fans, this happy band of brothers in their mid-20s reverts to being big kids playing superstars. Vocalists Bien-Aime Baraza, Willis Austin Chimano and Delvin Mudigi were high school buddies who loved to sing.

Upon completing their studies in 2006, as fate would have it, they met guitarist Polycarp Otieno and decided to form the Afro-Pop group, Sauti. They went on to become finalists in “Spotlight on Kenyan Music”, a competition run by Alliance Française, in the same year. “[Our] first shows were small and intimate. It was mainly friends and family who attended,” says Bien. By 2008, they’d signed to music label Penya Africa, added Sol (Spanish for sun) to their name and launched debut album, “Mwanzo”.

Thanks to singles “Lazizi” and “Blue Uniform”— and their imaginative, low-budget videos shot with and by friends—they soon became household names. Four years down the line, the band continues to go from strength to strength. Shedding their boyish image (wearing t-shirts with their logo embellished across their chests), Sauti Sol now goes for a more urban and sophisticated look (flamboyant, GQ-style outfits, courtesy of hot, local designers). And their shows are now sold-out affairs. Always live. Always with hip gyrating solos. Always. Sauti Sol also has a sophomore album to their name, and scores of high-profile local and international appearances.

Most notably, SXSW in the U.S., Mali’s Festival Sur le Niger, and Colours of Ostrava, the Czech Republic’s biggest music festival. Choosing to live together, the boys are able to watch each other’s backs, as well as keep to a strict, four-day rehearsal schedule to help hone their craft. “We want to be the best in the world,” says Chimano. Nothing illustrates this better than the current strides towards improving Sauti Sol’s musicality. Chimano now plays a saxophone; Bien, the acoustic guitar; Delvin is a force on the drums; and Polycarp has taken up the electric guitar.

These skills came in handy when celebrated South-African rapper/ producer, Spoek Mathambo agreed to collaborate with them on an EP. The resulting six-track album, released this June, showcases a new side of the boys that still rings true to their Afro-Pop core. It has also given Sauti Sol the confidence to begin tentatively planning their third album for possible release in 2014. For now, the band is focusing on a five-month long Safaricom Live Tour that began in early September.

The major series of concerts is taking the boys to towns they’ve never performed in before. And it also comes with another first, a revelation made on a chilly night as they headed home from a friend’s birthday dinner. Making an illegal U-turn, Sauti Sol parked their trusty jeep on the side of the road and took a moment to reflect as they gazed up at their own faces, finally, confidently, looking out into the world from a billboard. “There is no point of contentedness. The day you feel content is the day you stop being good at what you do,” reiterates Delvin.

For more information, visit http://www.sauti-sol.com/