Crown Xti Hum

[tony3d]

Just hooked up my Crown Xti-2000 to a Crown IC-150 pre-amp, and I have a lot of hum and some buzz. The IC-150 pre-amp outputs are going the Xti-2000 with an RCA to XLR cable. The hum is ridiculous. how do I solve this? I had and Onkyo M504 hooked up to the system just before I hooked up the Crown and there was no hum at all. Can I run the amp with nothing in the inputs just to see if it's the unbalanced leads going into a balanced inputs causing the problem? What about the hum boxes like the Rolls he18 or the Art Clean box? Can I just buy that? Oh and buy the way thanks for all this help. I posted on other boards and this has been the must helpful. Unfortunately my cable building*expertise is non existent. I have Attached a info on the Rolls unit.