When burning to a CD, i'm loosing about 6-7 dB with respect to the original signal

i like recording my own music, overdubbing vocals on karaoke tracks… and i get “commercial CD quality and volume”, but my problem is in the last step, when burning to a CD, i’m loosing about 6-7 dB with respect to the original signal… this happens regardless the laptop cd burner i use… the only common thing is that i’m using windows media player to burn them…

any idea?