Soundcard setup help

Hey guys,

Hopefully i'm posting this in the right place and someone can help. I'm new to digital djing and i'm looking for a little advice on getting up and running. I get the feeling that i'm missing something obvious but I have not been able to find an answer specific to my proposed setup so I thought I would ask you knowledgeable people for some help...

I have an M-Audio X-Session Pro controller, a Numark Stereo IO soundcard, and Traktor Scratch Pro on my Desktop PC. I installed the soundcard and followed the instructions to configure it on my PC. It is connected to my stereo from the output connection with a twin phono lead, and connected to my PC with a 3.5mm Stereo Plug To 2 x RCA Phono Socket. I have it plugged into the front left/right socket (the green one) on the PC. The X-Session Pro is connected to the PC by USB.

My problem is that I don't get how I can use this setup to cue tracks in my headphones. In Traktor preferences, when I go to the audio setup tab, I can see 2 options, my Realtek internal soundcard and what I assume is my Numark soundcard, which shows up as 2-USB Audio CODEC (WASAPI(Shared Mode)). It allows me to select it, but when I go to the Output Routing tab, I only have Speakers L R available to select, so I cannot set anything for Output Monitor along with Output Master (from youtube tutorials I gather I should have more options).

Can anyone advise what I am doing wrong? Do I have things wired up incorrectly? I have the x-session pro mapped via a downloaded tsi file, and it appears to be responding fine, so the only thing stopping me is this cueing problem.

Sorry for such a long post, any help appreciated!