do the plantronics dsp500 pull cpu cycles?

[cpush]

Ok, do the DSP500 (usb headset) pull from the cpu since they use USB? Or do they utilize the sound card ( i have an audigy 2 ) ? I have heard that it actually has a USB soundcard and that it rapes your cpu. From others I hve heard that it will not work without a soundcard as it uses the soundcard but just puts the signal from the usb port. Which is right? And does it take the sound from onboard or would it go from my soundcard?