Hi all, i have a VERY annoying problem here. I have a 24" iMac9,1. The first one that uses ddr3 type memory. it works completely fine EXCEPT it generates a very consistent hum on my speakers. I am using a pair of Monsoon MM900 2.1 speakers. It is getting so bad that I have to power off the speakers except when I am listening to music(that drown out the hum). The speaker is not the problem as I plug it in my unibody Macbook and the problem gone away. Also, it didn't hum when I hooked it up with my Core 2 Quad desktop. All my equipment is protect with a UPS. I did some research and people was suggesting it is a ground problem. I bought an very expensive ebtech ground filter. Nothing helps so far. Has anybody got any ideas? tx