Link monitor

Hi I am having an issue with Rekordbox link monitor. the setup is Macbook pro 2 x cdj2000 and a dim 2000. The only way I can seem to get sound from Rekordbox to the DJM2000 is with these setting. 

Djm settings 6 channel out 2 channel input

rekordbox

Link monitor off

Djm output

48k

Buffer 512

With these settings though the sound is very choppy, it sounds fine when playing with the built in speakers. 

Any help appreciated.