Static from tweeters, preamp?

I get audible static from my tweeters upon plugging in my onkyo p-308 preamp. Bad power supply, bad capacitor???? Poor solder joint?

There is very minor static, when preamp is unhooked. I plug it in and the static gets louder, much more noticeable. From what I remember, by B&K pro 10 mc also does this. B&K has 3 prong grounded, onkyo has 2 prong standard. When I used my Sunfire sig, I had no noise at all. It is a reg 2 prong plug. Help
Is any equipment new? I had some static issues with my new equipment for a month or two. It finally went away.
My monoblocks are 3 prong grounded plugs, preamp is two prong ungrounded, as is DVD player, cable box, TV. It is a static noise, not a ground loop low freq hum. Bad op amp? Preamp going bad, it is an old unit from the early 90's. I will be getting the sanders sound preamp in a few weeks, I'm praying it is the preamp.

All plugged now into a furman pl-plus C conditioner.

I had my other odyssey monoblocks hooked up to same upstairs set up, and sound Was still audible. Moved B&K pre upstairs, same noise. Basement setup now has odyssey amps , B&K pre, no noise, only sometimes. Maybe I'll check to see if the furnace is on, when I hear the noise. I'm at a loss as to what it is, I'm hoping it's the preamp, needs to be retired anyway.
Are you plugging in the preamp with the Furman PC power OFF?
You should be.
I leave the power off on the preamp when plugging in the cord to furman. I have had the power off, on, tried a different outlet, tried a different outlet with another power strip/surge protect, to no avail once the onkyo plugs in the ticking/static, similar to a light snare drum tapping the skin, driving me nuts.

I also think some of the hdmi may be causing it, but on a much less noticeable scale. When I unplug some of the hdmi cords from the back of the tv, it changes sounds in a very small way yet again. SON OF A..........

I'm out of my head.
Two hdmi cables into tv, one from cable box, one from DVD.

Furman has two isolated banks, I plug all components to one side, and only preamp/amplifier into the other. Yes I tried preamp in every possible outlet, as soon as plug hits receptacle, static hits the tweeters
I plug amps into wall outlet, can't hear anything at all.  

I plug in preamp, and there's the static.  Possibly preamp, but maybe my hdmi's cables are touching my rca's from amp to preamp. I rerouted every able , all power cables e together in a foam long tube.  Same sound.  I hope when the new pre comes, I don't have any of this static, I'll . 

I unplugged every very component one at a time, and when the preamp is plugged in, I get static, BUT....... when I turn the preamp on,. The static goes almost away, the volume of the static is cut in half, is going on ??????  
Pioneer dv48 elite was culprit, major static noise,.  Huh, cheap Sony replaced it via rca, no more static, well, a little, enough to live with for now.