DDJ-RB headphone cue delay compared to master

Hey, i own a DDJ-RB and am connecting this to my rokit 6's with a rca to rca cable. 
I use the ddj rb asio driver within rekordbox.

Now the problem; there is a small delay between the cue heaphones (tried 3 different ones, among senheisser-hd 25 and dt990 pro.

When i mix within the master cue and the cue within the headphone there is no problem. When i mix with only the cue on my headphones and the master on the speakers there is a delay.

I tried setting the buffer to the lowest setting it doesn't distort -->128. 

It annoys me so much. What can it be? have the latest drivers, firmware.

Please have a solution.