I have a somewhat different setup. I run my computer's audio through a Rotel integrated amp into PSB bookshelf speakers(well with 8" woofers, they hardly fit on the shelf, but)
I've been using headphones a lot more lately, and I can plug these into the amp and they work pretty well.
At work I bought a Creative SoundBlaster E1, to use instead of the laptop's onboard audio and in that combination there was a remarkable difference in quality. I was actually really surprised at how good that little E1 sounded as a sound card/headphone amp.
http://us.creative.com/p/sound-blaster/sound-blaster-e1
So I considered buying another one, and then I saw this Omni Surround 5.1. The E1 is slated more as a portable headphone amp, the Omni surround more as a desktop do everything.
What's intriguing to me about it is it has a microphone built in. It has headphone inputs on the front, and RCA jacks on the back so it ought to work nicely with my setup.
The real question is if the microphone works well enough with teamspeak. If not, there's also a mic jack on the front so I can do a modmic.