high frequency intermittent noise

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

https://clyp.it/4b233bmm

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.

james196911-12-2017 2:30am

james1969 OP Details Discussions Posts This discussion Message User 347 posts 11-13-2017 at 03:30am Copy Comment URL Report Comment Edit Delete @erik_squires The Furman looks promising. The P 2400 IT looks like the way to go.
Post removed Nov 13, 2017
james1969 OP Details Discussions Posts This discussion Message User 347 posts 11-13-2017 at 11:39am Copy Comment URL Report Comment Edit Delete @jea48 The noise does present itself 24 hours a day randomly, it is only the early mornings ~ 4am to 11am it is not very frequent, but it does appear. The building is 15 stories high. I have already had 2 different electricians in, and they did not do anything.
james1969 OP Details Discussions Posts This discussion Message User 347 posts 11-13-2017 at 11:50am Copy Comment URL Report Comment Edit Delete As I was writing my last post I realized another important fact: The subway runs under my building. I just noticed the noise appearing when I listened for a train to go by. There seems to be a correlation here, perhaps it's the subway system: when I hear the subway go by, the noise is apparent. That would also make sense in that the subway does not run as frequent in the early hours of the day.
willemj Details Discussions Posts This discussion Message User 1,036 posts 11-13-2017 at 01:39pm Copy Comment URL Report Comment Edit Delete I could not quite figure out what happened when yo used a battery powered radio. Does it come through your power lines or through the air?