piano teq demo

I downloaded the demo version but for some reason when I play the piano teq it doesn't sound close to the videos I've seen in youtube. I have a Mac with 10.6.8 operating system & I just plugged an audio cable from the headphone jack to my mixer with no external audio card.  Would like some help for one do you need an external audio interface to make the piano teq sound better & also the demo version is short of what the full version sound.  Would appreciate any feedback.

Thank you,

cvilla1973