Its endlessly fascinating approach to music makes f(x) the only K-pop group that can truly be described as avant-garde. Since 2009's debut single “LA chA TA,” the group has only grown more daring with each release. These songs cut up and reassemble time-tested genres like electro-pop and house into new and exciting configurations, such as adding unexpected melodic twists or turning gun samples and horror-movie strings into rhythmic elements.