Operator Error or a true problem.

I've recently bought a DDJ-SR. Love It. 0 problems does what it is suppose to etc etc... However, I also bought I sound monitor to use for gigs and in room when I practice. The problem the DDJ-SR sound inputs/out-puts are Aux or TRS, Duh. The thing is the guy at the store suggest I buy a TRS Dual Y Cable so I can send it straight into the sound board or sound monitor without having to use two cords. There is a gray and red color code to them and I'm not sure which goes where and I've tried both ways and the sound is very low and muffled the only time I can make it sound crystal clear is I plug the grey one completely in and the red one partially out. Is that a user error on my part? Is the cord jacks bad or is my controller bad?

Use the RCA Booth/Master 2 out.