DDJ-RR sound lag from headphones to master/booth

Just got the DDJ-RR, nice bit of kit.

But....

there is noticeable lag from the headphones to the master or booth output which makes it impossible to use. I have tried using different headphones, using different speakers, changing the buffer rate and nothing makes a difference. I have tried using different drivers in the computer and no combination makes any difference.

I have also tried having the controller plugged into the mains so that it isn't running off of USB power but still no joy.

If I can sort this then its going there is no point in keeping it because its completely unusable.

Please can someone let me know how to fix this!