When cueing a track on ddj sz2, main output volume goes up.

Just bought a ddj

sz2. Using with Djay and macbook pro 10.5. 

So everytime i press cue to solo a track, the main output goes up by like 10%. Will it be a sz2 problem, or maybe the unit i bought has a problem?

Also i noticed that when turning the cue/master knob toward the cue, the master audio never fully dissapear, and then when i reach like 1.5 on the left, the audio completely dissapeared. 

I'm just wondering how much more problem ill discover! I should probably just return the unit.