When most people hear the term ‘a cappella’, they think of cheesy show tunes, jazz squares, and spontaneous musical numbers. However, a cappella quintet, Pentatonix, is looking to change the stigma that goes along with using only voices– and no instruments– to create catchy, accessible pop music.

The group, comprised of self-described “choir nerds,” Scott Hoying, Mitch Grassi, Kirstin Maldonado, Kevin Olusola, and Avi Kaplan, first came together in 2011 after winning NBC’s competitive a cappella show, The Sing Off. Since then, they have made a name for themselves in the music industry, having released three EPs, two Christmas albums (That’s Christmas to Me was one of only four albums to go Platinum in 2014!), and, most recently, a full, self-titled debut album.

Previously, they based their platform mainly on YouTube, where they regularly posted covers of songs that ranged from Lorde to Ariana Grande, as well as catchy medleys that captured the musical careers of artists, like Michael Jackson. These videos were what gave them the most spotlights in the world. On their YouTube channel, they have over 9 million subscribers and over 1 billion channel views.

This past year, at the 57th Annual Grammy Awards, the group even won the Grammy for “Best Arrangement, Instrumental or A Cappella” for their Daft Punk Medley, which since has been viewed over 163 million times. They also performed at a sold-out world tour– the “On My Way Home Tour”– as well as released a documentary entitled The On My Way Home Project.

What could be next for the a cappella sensations? The next big move for Pentatonix was to shift to all original music, completely deviating from the covers that their fans had come to know and love. This risky jump they made completely paid off.

To prove that they could make a name for themselves, the band began writing original music, and released their first original single, “Can’t Sleep Love”, on September 4th. Since then, it has been climbing the charts and has just recently cracked the Top 40.

Their self-titled album, Pentatonix: Deluxe Edition, was released October 16, 2015. It features 13 original songs, as well as four covers of hits, “Cheerleader,” “Where Are Ü Now,” “Lean On,” and “If I Ever Fall in Love.” After a neck-and-neck battle with Demi Lovato, who had also just released a new album on the same day, the group’s album debuted number one on the Billboard Top 200 list, a massive milestone for the musical underdogs.

On the album, they collaborate with musical star Jason Derulo on their cover of “If I Ever Fall in Love.” The album features many songs that are energetic and fun, like the third track, “Sing,” for which they just released a music video. An unexpected surprise is Track 13, a slow, but beautiful, lullaby called “Light in the Hallway.” The last track on the album is a remix of their single, “Can’t Sleep Love,” with an added rap bridge by Tink. A special Target edition of the album features a bonus track, “To the River.”

The most progressive and unique aspect of Pentatonix: Deluxe Edition is the lack of instruments used. As anyone can imagine, it is difficult to make pop radio hits, which are typically energetic and loud, with nothing but five voices. However, with Hoying, Grassi, and Maldonado as the vocal leads, and Olusola and Kaplan as the beatbox and bass, the group has managed to make catchy, accessible, and fun tunes that still maintain the integrity and uniqueness that make them the front running a Cappella group in the music industry. Pentatonix surprises everyone who hears their music when they discover that no instruments were used to create the infectious beats.

With the successful year they have had, a Grammy under their belts, and, now, a top-of-the-charts debut album, Pentatonix is definitely beginning to attract attention all over the musical world for being a leading pop band fit to rival anyone.