2. Rotate the guitar so that the neck is perpendicular to the computer, monitor, pedals, etc. the pickups act really funky with electronics...learned from experience.
3. Mess with your power arrangement, The way you have your computer, preamp, etc plugged in can affect the amount of noise you get. If you can do two power trees, split the preamp off into a different power outlet/tree. If you can actually get it to reach a different circuit in your home, that'd be the best.
4. Turn off any and all unnecessary electronic or mechanical devices.
I'll post some more ideas later after I can research your particular preamp...until then, I hope this helps!