Popular duo Akdong Musician made a 180-degree turnaround from their previous image for their latest performance on 'K-Pop Star 2'.

Titled "Optical Illusion", their newest song featured a slightly darker, melancholic theme from their usual upbeat performances, and also featured a more complicated chord scheme and melody.

"I kept trying to figure out the first chord," J.Y. Park confessed. "It's a very difficult chord progression they're using. I don't know how the public will receive it, but personally, I could listen to this song for a long time."

"To be honest, it's not a very public-friendly song," Yang Hyun Suk added. "But maybe that can be your strong point, as well."

With this performance, Akdong Musician secured their position on the 'Top 10', and will be advancing into the live competitions. Catch the full episode below! [Akdong Musician's performance begins at 6:20 in the second video.]