Reply to Audio Problem on S4

Hi guys, I have been having problems with my audio on the S4 and the problem is that when I load a song to any deck and crossfade to listen or mix it the volume is always high even if the volume on that deck is low, so i have move it up and down to bring it at the volume desire...what the heck is the problem? is it software issue or hardware (S4)?

Help please guys
Thanks....