PCI card v. USB is an interesting topic. It seems you can't make a general statement that USB DAC is better than sound card S/PDIF to DAC. USB timing is an issue that needs to be addressed.
For example: the Peach Tree Audio Nova has both a coaxial input as well as USB. The Computeraudiophile review preferred the sound card S/PDIF to coax input over the same computer connected to NOVA's USB.
"the Nova sounded better than the other components and configurations using Windows 7, J River Media Center, WASAPI + Exclusive Mode, and ASUS Xonar Essence STX outputting bit perfect audio via coaxial S/PDIF to the Nova's coaxial input number one"
http://www.computeraudiophile.com/content/Peachtree-Audio-Nova-Review-Part-IIThe ASUS card is on that site's recommend sound card list.
I am trying to determine how to get the best sound out of my PC for under $2k (ideally <$1500). At $4k there seems to be some well regarded options:
* sound card & DAC?
* just a DAC w/USB input?
* USB to S/PDIF reclocker plus a DAC?
* etc.
If sound card to DAC then is ASUS enough or would there be better sound using a <$700 like Lynx or RME?
I am currently using an m-Audio Revolution connected to my pre/pro DAC and I would like to upgrade. I run JR RIver with ASIO and control with a laptop using remote desktop. The PC is in a closet with cable through wall to electronics (so it's dead quite in listening room).