Unless I'm wrong (and that is a possibility) you shouldn't really need noise reduction. My guess is your mic cable is adding some noise to the recording. If not the cable, then something in your signal path. ...
The other thing to consider as far as getting a good signal, is your routing. I don't know "Audition" so I can't go into specifics, but it sounds like, maybe, you're routing options are jacked up a bit, but I truly don't know. With even lower end M-Audio units, you should be getting plenty of gain and a good signal to noise ratio. Come to think of it, a fautly mic cable could cause low signal and high noise. Try swapping out your mic cable and see how much that helps. If I'm way off base we can re-evaluate.