high frequency intermittent noise

I have a noise issue that is intermittent.  Here is what the noise sounds like:


Here is what I know so far:
  • The sound affects all components and is compounded if all components are turned on.  I have turned off my preamp, phono preamp, leaving just my mono blocks on, and the noise still appears.
  • I have turned off everything and unplugged everything in the house including my dimmer switch, and the noise still appears.
  • I have a pair of pro-audio monitors, self powered with class AB amps, and when I plug those into the same outlet, I hear the same noise coming through the pro-audio monitor.  So this rules out my big system.
  • The noise is primarily during the day and goes into the evenings, weekends too, early mornings it does not appear.
  • I live in a pre-war mid-rise building.  I have no ground, I'm using a Nordost QKore grounding system.  This did reduce the noise floor quite a bit, but has no affect on this intermittent noise.
  • I have a cell phone tower directly across the street from my building in Manhattan.
  • Looking at a real time analyzer, I see peak at 2kHz when the noise appears.
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I found a set of RCA shorting plugs. I turned everything off except for one mono block, inserted the RCA shorting plug, and the noise is still present.

I tried a different power cord, and the noise is still present.

I tried an XLR cable between my power amp and preamp, the noise is still present.

I have ferrite beads (made of material 61) on order.
Sweet lord, you poor man.

So.. Those copper mesh curtains.. You could lay one on the floor, stack your equipment on top, then wrap the curtain up and over, creating a true faraday cage, as long as you remember to ground it to a pipe or the ground in your outlet. Test to see if an actual faraday cage works.. If so, you could build a nicer looking one integrated into your rack.
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The power cord is my antenna, I switched to a non-audiophile power cord and was able to move the power cord around, up, down, and around (could never do that with what I am using), and yes, I could affect the noise.

I'm wondering if I'm now in the market for a new power cord?