upgrade m-Audio Revolution card? CASH card or just USB DAC?

[Vectra]

Would there be a sound quality improvement upgrading my old REVO card to ASUS, RME or Lynx recommended on this site? Or, is the m-Audio REVO just as good at passing digital over SPDIF?

 

I currently use my HT processor DAC but have also considered an external DAC which makes me question why I need a sound card at all. How about just using something like the Benchmark, Wavelenth Proton, or PT Nova USB connection? PC>USB>DAC?

 

In reading the Nova review on this site it seemed like the ASUS card to Nova connection was preferred over 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"

 

This seems to indicate that adding a sound card is an improvement over simply connected with USB. I then wonder if my REVO is as good as the ASUS or should I upgrade (back to my first question)?

 

 

MY System idea (I want to have a multipurpose7.2 HT & 2-channel setup):

PC (xp or win7) w/JRiver MC -->sound card-->DAC such as Benchmark, Nova or Proton...leaning towards NOVA--->HT Pre/Pro+amps (could try Nova HT mode or even swap cables elimating pre/pro for 2ch). Remote control using HP Slate and remote desktop (unless there are better ideas)...currently use a laptop.