Hi, maybe the hardware selfs could damp your output.
Try to check the SZ Utility mode - Manual - 5.Changing the Settings
I have set my DDJ-SX master output tresshold to -0,6db
edit:
remind that the mixers like DJM 700 are basically analog mixers, they could clip the sound without cracking the sound.
but its a different story with the Digital mixers like the DDJ is.
You have to make sure that your audio files you would play are full analyzed. Also check your mixers Gain, Lower the Channel Outputs to 0db at every mix situation, otherwise the Software (as well as Traktor and Serato) will compress the sound (if not Deactivated *realy not recommend, trust me*
hope that helps a bit :)