ddj sz mater volume is not loud enough :(

I own a ddj sz and a xdj rx , with rekodbox dj , when I use the ddj sz , the volume is so much weaker then xdj rx ..

the xdj rx respond to the mixing cross fader curve that is on the controller menu , use the last curve and u get the best sound from it and it is awesome . To do this on rekodbox dj >preference ( the star thingy )>controller >mixer > logarithmic curve, . U will get a very goooood sound and will be very happy with xdj rx , but I don't know why , when I use ddj sz the sound sinks so bad and it doesn't respond to any of the 3  curves from the menu . the only respond is from the local knob at the crossfader curve on the front (edge) . I hope pioneer can do something about this and if the DDJ SZ can do the same as XDJ RX .. it will the best ever controller machine in this world . I hope pioneer will look into this