Reply to Allen and Heath Xone:DX Question

Alright, so I am strongly considering purchasing a Xone : DX within the near future and I had a quick question to anyone that has one or knows the answer to my question...

Straight out of the box, do you have to hook the controller up to an external audio source (Speakers) in order to get sound or can I just listen off of my headphones? I wasn't sure it was mandatory to hook up to an external power source (speakers/amp) to get sound or if I could just listen off of my headphones?

I apologize if this is a repetitive or "dumb" question.

Any feedback is greatly appreciated.

Thanks,

Rob