DJiO2 w/ djay Pro 2 headphone issue

So I use a Numark Mixtrack 3 as my controller. When I cue my tracks via my external audio interface (the DJiO2), the audio is pretty poor quality. My headphones work just fine, but sound awful when I listen through the DJiO2. I’ve adjusted volume and cue gain on both the DJiO2 and the controller, quality doesn’t change.

I did need to use a 1.5 inch jack attachment for my headphones in order to use them on the DJiO2, but I doubt this is the issue (unless I purchased a cheap 1.5 inch jack).

Does anyone know how to troubleshoot for this kind of issue? Thanks!