For most fans of the chart-topping K-pop quartet SISTAR, if the group's 2011 track "Over" is known for anything, it would likely be band member Hyolyn appearing to lose her footing during a performance of the song on Korean television, shortly after its release.

This is a pity, since "Over" is a highly overlooked gem from the SISTAR catalog.

With a hard-edged urban sound and edgy, super-charged vocals devoid of digital gimmickry, the song shows an entirely different and virtually untapped dimension to an already versatile act with no shortage of vocal talent.

Taken from the group's debut album "So Cool," for which South Korean wunderkind producer Brave Brothers contributed seven out of 12 tracks, "Over" includes siren sounds and squealing synthesizers, straight from an early Prince album.

Like many other Brave Brothers songs from the same period, the producer appears to be trying out any sound he can think of, pushing the group into new areas that would almost be unthinkable now that they have proved themselves as a top purveyor of pop ballads.

That's not to say the four members of SISTAR don't still likely have some more surprises left in store for us. But the music industry has a way of pigeonholing an act, once they have had success with one particular style or sound.

Listening to the dozen tracks on "So Cool" it's hard not to be struck by just how much the songs vary in sound, style and feeling.

Though a lot of music moguls in expensive suits will mutter a lot of mumbo jumbo about the importance of band "branding," as a listener, it is this exact kind of eclecticism (often seen in hungry new artists as they struggle to find the sound that will define them) that makes "So Cool" as strong as anything the group has released in their five years.

Listen to SISTAR's blistering 2011 track "Over" RIGHT HERE