Trying to Sample from iMac>Audio Interface Digital Outs into

Trying to sample from my computer (iTunes, VSTs, and youtube) into my MPC 2500 JJOSxl
I can't seem to get sound monitoring on the MPC

I have a Roland quad capture.
I am running the digital in and out of Roland into the digital in and out of my mpc
I have my 2500 on the record screen.
INPUT:Digital
MODE: Stereo
Monitor: On

I have the interface setup as the input and output audio in my iMac control panel settings.

I have tried sampling iTunes, youtube and virtual instruments/recorded audio in Studio One Pro 2.

This should be easy I assumed but I am obviously missing some step here.

If anybody could help me with this it would greatly appreciated.

I have recorded out of my 2500 digital outs into Studio One just fine.

Interface is 24bit, MPC is 16bit...Doh

Thanks man