DDJ SZ Distortion

Hello, I recently began to have problems with distortion and lower overall output from my DDJ SZ.  There is basically noticeable distortion when either the line or the master get over +2.  The overall volume is also very low unless piped through a mixing board which boosts the output to the speakers and allows me to stay at 0db on the SZ.  I did not notice this issue until recently when I started going direct to the speakers with my SZ instead of through another mixer.  I have had the same problem with multiple computers running both Serato DJ and Virtual DJ.  Any suggestions about what this could be?  I have tried using proper gain structure and the problem still exists. Please help.