DDJ-400 Delay when using PC Master out OR High Pitch Noise when using RCA

Hi,

I have just bought a DDJ-400 and have been excited to use it. 

I had planned to use the PC master out to run the audio through my PC and out of my Production monitors using my Focusrite Scarlett 2i2. However, when i do this i am getting a delay between the headphones and the speakers. 

I thought i would try the RCA out as an alternative but as soon as i plug the RCA into my Monitors i am getting a high pitch squeal through the speakers. 

I tested the USB in different locations in my PC but got the same squeal however this does go away when i unplug the USB cable. 

HELP!

Currently, i have no way of using my DDJ!