Mad unclarity and muddyness from my amp when I record guitar?

Question

I'm using a 1/8th to 1/8th adapter along with a a 1/4th to 1/8th adapter to plug into my computer. I have a Line 6 Spider III 15 amp. I'm putting the 1/8th side into the slot where I'm supposed to put the microphone. It sounds ok clean but any ammount of distortion sounds horrible ): I've used all kinds of different combinations of lower gain and volume but no avail ):

Answer 1

this is your savior

http://www.guitarcenter.com/Line-6-ToneP...

use it all the time. if you dont have the money then just buy the 49.99 one