If you have a noisy systems you will have problems no matter what (SS or not). Things like spindle motors, pump motors, etc all generate lots of noise. I have found a good line filter:http://soigeneris.com/cncparts2.aspx , mounted in the mains feed as close to the source of the noise is the best way to get the noise out. Also, properly routing your cables, keeping the noisy lines away from low signal sensor lines will help a bunch too.