Since winning season three of NBC’s “The Sing-Off,” Pentatonix has risen to national fame. The fierce a capella group now travels the world, performing covers and medleys of popular songs using (usually) only their voices. The group has been known for some amazing performances, clever mash-ups, and touching songs – but we have never seen them do a more haunting cover than this.

“Say Something” by Great Big World and featuring Christina Aguilera was a gorgeous ballad that hit the radio scene in 2014. The song tells a story of two lovers who are letting go of their relationship after years of trying to make it work. This somber story plus the haunting piano background, the moving vocals of lead singer Ian Axel, and Aguilera’s sultry tone make for one tear-jerking song.

I know I’m not the only one who’s tear up listening to it on the radio!

Well, as Pentatonix does, they decided to do an unbelievable cover of the song, with female vocalist Kirstin Maldonado and bass singer Avi Kaplan taking the lead on this one (the group rotates who sings lead on each of their songs). The two other male vocalists Mitch Grassi and Scott Hoying took backup, gradually joining as the song came to a climax with the full-group singing in four-part harmony.

This video is a little different from regular Pentatonix videos for one big reason: it’s not entirely a capella. Extraordinary beat boxer Kevin Olusola usually provides background beats using only the amazing array of sound effects he can make with his mouth. However, for this video, Olusola shows off yet another skills that this talented musician possesses: playing the upright bass.

While Olusola plays the bass incredibly (almost as incredibly as he beat boxes) and the string vocals are perfect for the original arrangement of this song (in the original song, a string orchestra joins the vocalists and pianos throughout, gradually swelling to the end), this technically makes this number not ENTIRELY a capella.

We’re willing to forgive them for mixing it up, consider how gorgeous this number came out.

What we love about Pentatonix – and there’s a lot of things we love about Pentatonix – is how they film their videos. They don’t over complicate things, they don’t try to turn each video into something along the lines of a concert performance. They simple sit and perform; and as a vocalist, you learn sometimes that can produce the most haunting performances, rather than trying to compensate with unnecessary movement.

The group sits on a rustic set; Maldonado sits center on a large, vintage chair with Kaplan to her left sitting on a wooden ladder. Olusola sits on her other side in a wooden chair with his bass and the other two vocalists stand behind them. There’s something very beautiful and very sad about the whole setting.

And the entire number, all five performers are acting the song beautifully. You can see the emotion in their faces, the pain in their eyes – Kaplan is burning us with his piercing stare directly into the camera. They FELT this song, and it was clear in the staging and their gorgeous vocals.

What did you this of this (almost) a capella cover? Did it give you the chills, too? Share your thoughts in the comments section below.