Just thought I'd let you all know that I got it all fixed up.
Easiest fix ever, $15 ground loop isolator, done.
Now instead of a 6 foot rca splitter out of the soundcard to the line driver, then a 3 foot rca cable to the amp, I have about a 4 inch long rca splitter out of the soundcard, then that goes directly into the isolator, that goes directly into the line driver, and that goes to them amp with about a 6 inch long rca cable.
Absofreakinlutely no noise, I love it. Now that my amp is being fed the actual bass channel from a nice computer sound card that sound quality is just absolutely amazing. The bass hits so clean at just the perfect spots, and I can set the exact crossover frequency from the touchscreen without having to even touch the amp.
So for those of you with creative cards and weak bass, it can be fixed! Just make sure you cut your RCA cable's length down to absolutely as little as possible, use the sub channel not the mid channel, and most importantly if you have a group loop isolator hook it up BEFORE the line driver, that way it amplifies a clean signal instead of trying to sort through a loud *** noisy signal, which doesn't work at all.