Starting Cubase - Tinny Sound

So I just bought the UR22 MK2 and it came with Cubase (8).

I’ve installed everything, and once I got to setting up the sound, and listening to it - it sounds very tinny… as if I’m in a spaceship or something… I have one of the newest macbook models…2.7 Ghs Processor…
So, I’m not sure the problem.

If someone could help, that would be welcomed.