I see that, I'm leery of dropping too much $$$ on a sound card because I don't want the quality of the card to outstrip my speakers by too much. Not a whole ton of point if the speakers can't put out quality sound to match the card
I agree 100% if you are pushing speakes sub $300 then there is no point in getting an expensive card. I would say just get the ASUS DG should be all you need.
There is also an ASUS DS which is just the PCI version of the DX which is $49.99 $39.99 after rebate. This card will be a good basic card that has really good sound quality I use one of them in my HTPC rig.