...I assume you mean the headphones, and not the Razer Barracuda soundcard...
In practice, the Barracuda's (the headset) sound much better with a soundcard, although other 5.1 headsets I've tried have sounded better overall (although I note, all my headsets since my barracuda's have used digital and not analog).
Really, once you get to 5.1, a soundcard is really needed to get the most out of youre sound system.