In early November, one cluttered corner of the NPR office in Washington, D.C., received a new type of memento. As global superstars SEVENTEEN became the first K-pop group to make their official Tiny Desk debut in the U.S., their light stick took its rightful place on the set’s iconic bookshelf alongside a hoard of trinkets left by previous musical guests, including Sabrina Carpenter’s bedazzled martini glass — and Billboard was once again on hand to witness it all, from rehearsal to goodbyes.

While a few offshoots of NPR’s concert series have welcomed K-pop acts in the past, SEVENTEEN members Joshua, Mingyu, Seungkwan, Vernon and Dino were the first to perform behind the actual desk. And filming in the office base meant the most rigorous of standards were set in place: no floor monitors, no in-ears, no post-production magic or vocal touch-ups. Taken together, these are no small asks, even for veteran performers now a decade into their careers.

Then there’s the matter of size. “Any group with a large number of lead singers is hard to bring to the desk,” says Suraya Mohamed, executive producer for NPR Music, who adds that vocalist DK was originally supposed to attend the shoot before losing his voice. While a sprawling ensemble in its entirety may technically be able to squeeze into the space, she explains, that’s without accompanying band members and several instruments. Plus, only around five or six people comfortably fit in the front of the desk.

All these challenges combined, beyond creating the raw, authentic atmosphere that Tiny Desk has come to be known for, stretch artists to reach new highs, say its producers. And trust SEVENTEEN to rise to the occasion. All the world’s a stage for K-pop’s main theater kids, who recently wrapped the U.S. leg of their NEW_ world tour. Whether they’re playing to 18,000 cheering fans or an office of public media employees, it’s hard not to walk away from one of their shows inexplicably and irrevocably charmed.

In the video posted to NPR’s YouTube channel on Monday (Nov. 24), the group confesses to having experienced some nervousness before the shoot. But while working through a medley of nine songs spanning years of their catalog — from blistering hits “Hot” and “Clap” to beloved b-side “To You,” with a fair share of stellar high notes sprinkled in — those nerves were more than melted away by the warm reception in the room. “I don’t think I’ve ever seen such a response on Tiny Desk,” Vernon says, visibly blown away by the energy the crowd gives them throughout. “This is awesome. Thank you so much.” 

Given all that went on behind the camera, here’s a roundup of 3 things you didn’t see in SEVENTEEN’s Tiny Desk debut.