[dsraven]

you could lose some of the compressor noise by plumbing the air intake to the outside of the building. I have mine plumbed into the attic of my shop so most of the pump noise isn't in the same area as I am working. it makes quite a difference in noise (IR 80 gal 2 stage, 5 hp). you can hear it when outside but it is muffled by the enclosed area, attic insulation and the roof vents. i used, like, 3" or 4" pvc pipe with an s10 air box and filter on the end. it also keeps all the ambient sanding dust or grinding dust etc out of the compressor air pick up and allows cold air from the attic (in the winter, we have more winter than summer here) to help cool the compressor head and also cooler air has less moisture than the warm shop ai r so less moisture to drop out in the compressor tank. I have an electric auto drain connected to the shop lights so if the lights are on the auto drin is working. if the lights are off I'm not in the shop and the compressor is off anyway.
anyway, just a thought. how much air does your plasma use, typically?