It's just an awesome sound. There's something really piercing about it. I'm not wondering about their vocal abilities, just whether there's some kind of tweaking going on to get that clear sound. It's a hard range to sing in without sounding strained. The woman in black, in particular, has a really great distinctive voice. Maybe it's that they are singing in unison, so there's like a natural stacking effect going on, plus the high range.

I also really like the rapper! Kinda like Hyuna before Hyuna became an aegyo monster/retreated into baby talk ala Britney Spears.