M-Audio 410 Noise

First off I apologize if this has been covered but I looked through the page and didn't see it.

I have had my 410 for a good five years now and has worked well for quite sometime. However, once I plug in my power source from my mac, it sends a high frequency hiss sound through my two outputs that I am using. Obviously when it isn't plugged up with power, there is still sound sound but not nearly as much.

So what I have done is the following: I have a furman mx-8, running a firewire cable from my mac to my maudio device and I have two balanced 1/4trs to XLR going from my outputs into my stage box.

I have tried replacing cables = didn't work
I have tried plugging my power until a different outlet on another socket = didn't work
I have replaced the end of my charger to be a two prong instead of three = didn't work

So needless to say I am at a loss of ideas. I would love to keep this plugged in because I use my computer for worship music on Sundays and Wednesdays. There is nothing worst than your computer dieing when you are running loops and a metronome for your service. Any advice is welcomed.

I am running a Macbook Pro 10.8.5, 2.5 intel core i7 16gb ram

I have also replaced my computer and the problem still persists....

Thanks in advance!