Connecting BX5 D2 Monitors to Headphone output?

[Promedeus]

Hi everyone! For Christmas I got a pair of M-Audio BX5 D2 Monitors (http://www.m-audio.com/products/en_us/M ... D2New.html) and I just have a quick question about hopefully connecting them to my existing audio card.

Currently I have the ASUS Essence STX audio card (http://www.asus.com/Multimedia/Audio_Ca ... sence_STX/). It is really designed for headphones, and was their primary use, but I have also used it with a home theater system before.

Right now I have the BX5's connected to this by using a TRS splitter that comes out of the Headphone out (TRS) on the card, then the two split TRS cables go to their individual speaker. Although, the speakers are defiantly not playing correctly.

Can I get this card to work with these monitors, and how would I do that?

Thanks so much for your help,
Chris.

[Promedeus]

Would this do the trick?

http://www.guitarcenter.com/Live-Wire-3 ... 1166742.gc

EDIT: Would that be unbalanced though? If so, what is the quality difference between unbalanced and balanced. Is it even noticeable?