Akai MPC One. No sound out of headphones.

Hello everyone. New to the MPC world. I am able to get sound out of my MPC in controller mode. However, while I was in standalone mode or controller mode, my headphones get no sound. I used two different headphones but neither work. Is there something I'm missing?

There's a volume knob on the back? lol do you get sound out of the 1/4 inch jacks on the audio interface?

DOH!!! Thanks Ultros. Yes I did get sound using the 1/4 inch jack.