dj control instinct headphone problem w/djuced

hi there. i am having a problem with the dj control instinct i recently bought.

i want to play the main mix out of my computer speakers (mac osx 10.9.4) and preview the incoming track through my headphones. i select the hercules djcontrol instinct aggregate audio device. master is set to 1&2 and headphones 3&4. trouble is, this configuration only plays the preview through the headphones. when i select my computer as the output, nothing comes through the headphones.

any help would be appreciated.