Ralph, I'm not sure what you are talking about regarding the chassis ground. I am plugged directly into the wall outlet and my preamp is dead quiet. Do you still have a hum problem?
Joe, glad to see that you have received your preamp. I am anxious to hear your evaluation. The preamp will take a couple of days, however, to break in to achieve its smooth character. I definitely recommend the best power cord for it. Interesting that you got a hum on RCA. I only have the single RCA outputs and never had a hum. Must be a system dependency issue.