Using my old mix track pro, plugged in to my Mac. Connected speakers through RCA output, plugged my headphones in via the Numark MTP and cannot for the life of me work out how to get pre cueing to work!

Anyone know?
Starting to grind my gears…

Just want to add, that when i choose split cue, i can hear through the headphones. But cannot just have it on it’s own i.e to pre listen to a track before bringing it in.