Kurt has made an excellent point. Check the gauge and an industrial noise filter might make sense.
P.S.: You might check on Audiogon here. Someone has reported on his set up specific to your problem some while back. Sadly I don't remember who it was.
P.S.: You might check on Audiogon here. Someone has reported on his set up specific to your problem some while back. Sadly I don't remember who it was.