External Sound card on Power Mac

I have a powermac G5 and a Creative Audigy 2 NX It is the external USB 2.0 soundcard. When I had it plugged into a windows computer I was able to configure the 5.1 sound option on it and everything and I could use all of the features. But when it is plugged into my PowerMac I can access its settings in system preferences and it sees it and uses it as the sound output, but it only has a left/right volume slider and no other controls except master volume, the box plugs into the usb of my mac and the digital out on the mac goes to the digital in of the NX. Is there a utility or something I can use to get access to the other features of the soundcard?

--Thanks

Creative hasn't made anything to support the Audigy series in OS X so you are out of luck

are there any good surround sound cards made for my powermac?