I figured out the problem, but I'm almost ashamed to admit it. Apparently the volume knob on my headphones was set really low and I didn't notice. So I was maxing out everything and it was still really quiet. Since I had just installed Mandrake, I was guessing that the problem was within Linux... not the headphones themselves.
Thanks for the responses. And I looked at ALSA and it looks pretty impressive. I may try it out.