Later in 2004, the group was recognized for their vocal ability with numerous awards, including nominations for Best Newcomer at the Golden Disc Awards and the Seoul Popular Music Awards.
On March 29, 2005, SG Wannabe released their second album.
Both versions of that song were recorded with their former member Chae Dong-Ha, and new member Lee Suk Hoon made his debut performance on April 24 on "M!
Count Down", singing the first track, "Lalala", on the new album. They also released another song that has become a famous OST in many dramas titled "운명을 거슬러" ("Fate Reverse") Former member Chae Dong-ha committed suicide on May 27, 2011 after battling with strong depression since his SG Wannabe days.
Selling almost 200,000 copies, The Sentimental Chord was the best-selling album of 2007 in Korea.