this could help.....level settings
This may or may not be of use to you.....
I have personally experienced a similar 'hissing' low, distortion sound when going through my j-station to my audiophile 2496, although these are different cards and pre amps the same rule may apply.
The hissing distortion noise may be coming from surrounding frequencies; If your set up is in a room which has such things as TV's, radio's, or any other technical equipment, and your computer and/or guitar is positioned near them whilst recording, these can interfere with the sound being produced. Try positioning your guitar alittle further away from things like PC monitors and TV's and/or try turning the Gain levels down a little.
Also a way of instantly finding out if it solves the hissing is running the sound in real time (Dependant on what software your using as to whether or not you can do this) and try moving around and playing the the gain and effects levels.
Another good way of setting the recording level to the right volume so as to prevent such hissing noises and interference is monitoring the inputted sound, again dependant on which software your using and card, usually there is a peice monitoring software privided with soundcard, usually found in the 'control panel' and/or under the 'sound devices' settings.
Hope this helps somewhat...
Sorry if i am rambling unwanted rubbish.....
regards
aL