Hum and hiss with Rives Parc

I have recently installed a Rives Parc into my system. It has introduced an annoying hum and an audible hiss. I have isolated the earth temporarily and eliminated the possibility of a groung loop. I have tried a different power cord (Eichmann Express) to no avail. Has anybody else had a similar issue with these units? If so any help would be appreciated. I am using a Chang Lightspeed power conditioner.