If you want to make your compressor silent you will have to make a box similar to the old Impact-Printer boxes.
Basically a box with vents on 2 ends(shouldn't need a fan), a lid and foam glued to the inside.
Best stuff I think is foam that looks like the old cardboard egg-trays, but this would mean that the box needs to be considerably bigger than your compressor to allow for about 1" of airflow allround.
All in all should be easy to construct.