It's always interesting to see an artist's first step in becoming a singer. Through the recent episode of MBC Infinity Challenge, audition clips of SNSD's Seohyun, SHINee's Taemin, f(x)'s Sulli and Krystal were revealed. And of course, the highlight of this episode was the Infinity Challenge crew undertaking the mission of becoming idol stars. They headed over to SM Entertainment that day for auditions. Cute audition clips of trending idol stars were revealed through this episode as well. f(x)'s Krystal had an innocent image that matched well with her long, black hair. Despite her young age, she radiated with a model vibe due to her slim, S-line body. f(x)'s Sulli and SNSD's Seohyun's cute and young faces could be seen in their audition clips. Seohyun sang a children's song while Sulli confidently auditioned without showing any signs of nervousness. SHINee's Taemin impressed the judges with his powerful popping and flexible dancing skills. As for the Infinity Challenge crew, all of them unfortunately didn't pass through the auditions. However, they aren't going to give up. In order to prepare for their idol debuts, the Infinity Challenge crew officially started to make their demo tape. Meanwhile, check out the cute audition clips of the idol stars!