Cut Karaoke伴奏

As i know, there is a program named GoldWave. This program can help you convert a song into different stereo range. You can search for the program and give it a try. After you get the program, basically what you have to do is: go to Effect>Stereo>Reduce Vocal. The outmake quality of the song may not be perfect, but at least the main vocal is reduced.

Hope this could help you out~