When you say Proper Electrical Ground, are you talking about the one outside at the meter? That's the first place I'd look. I had the same problem about 10 years ago. To remedy it I ran a separate wire through the wall to a stick of rebar outside that I drove a couple feet down into the ground. All static disappeared.

Yeah- it looks like the ground is attached to a piece of rebar. I didn't really want to do it but I ripped apart my power cord routing to separate the mixer power supply from the other electrical units. Through this I was able to pinpoint the source as the board. I ended up plugging it into a separate circuit and the comb filtering (is that what it's called?) is incredibly less. Barely noticeable in the monitor channel now and nothing detectable in main path.

I can live with this now.

You're on the right track.
It could be a bad ground in the Furman or the outlet strips.
Open them up and see if the ground wire is loose in any of them.

Disclaimer!
(Turn off and unplug everything first)

I agree, it's most likely a bad ground. I wouldn't say this is good advise, but I was recording a band playing live and had horrible noise when the computer was plugged in. I was able to remove all of the additional noise casued by the computer by putting one of those .50 cent ground isolating plugs on the computer. Just in case you don't know what I am talking about, it was one of those adapter plugs grandma had to plug her air conditioner into the old two pronged outlet. That isolates the ground noise made by the computer. Got me by in a pinch, don't know that I would make it a permanant fix.

The singer / guitarist of one band I work with has a ring in his bottom lip.
He learned real quick what happens when you lift the ground like that!

Zap!