noise from Mac Pro?

Hi all.
Put together a small studio here. In getting things up, there's a noise that comes through the monitors, accually 3 at different times. none, less, greater. hum, jacobs ladder sound, clicks.
Currently there's 3 things in the chain, mac pro, 003 digidesign rack,jbl active monitor speakers.

Everything is fed from a furman balanced (iso) transformer....

Mac > firewire to 003> spidf to jbl's.

The sound seems to mimick or be in harmony with the computers hard drive and or fan.

Checked for bundle , parallel wires, pull plugs,, etc....

I feel it's from the mac. But?

Has any one run into this problem and fixed it.

Is it a known issue.

thanks in advance for any advice.....Rich

This doesn't really help you but I'm getting my 003 in the mail tomorrow for my macbook pro. I'll let you know if I run into any trouble.
Do you have a cell phone or any other wireless devices around? That can cause issues sometimes... For example.. If I'm playing guitar with a cell phone in my pocket it will create a hum and click. I'm sure you are aware but I thought I'd bring it up!

I am trying to understand your post correctly. You hear HD or fan noises through your JBL speakers?
The fans on my Pro run silently. I use the standard audio out to my home theatre setup and I've never heard any feedback or anything like you describe.
Do you a pair of different speakers you can test?