Best home cinema sound card?

Hi all,

I am currently building up a new PC (or maybe HTPC) for my home cinema.
I believe I have a good sound system (Polk T2600 & Denon reciever), however the saying is "crap in, crap out" - so i wish to make sure the sound quality this system gets is great.

The main use for the system is movies&TV. I also hear music, of course, but the priority is movies.

I was thinking of the ASUS Xonar D2X for sound card,
however it is quite an old model and i just don't know if there are any better today for DTS & Dolby support for home cinema.
Please advise if you know of better models (or if this one would be great as it is).
I'm not looking for the cheapest card, just the best for movies.
Thanks!