I have finally figured out what was causing a very high pitch noise that came from my computer power settings and would bleed through faintly into my monitors.
This have been driving me craze for over a year.
I thought it was my trusted Zoom R24. Now I have a new UR-44 and still had the problem.
I was ready to purchase a new PC.
My UR-44 feeds the Nano Patch and the Nano Patch feeds my powered monitors.
As the computer is tasked, the high pitch would be audible with my power settings in Windows set at "Balanced".
If I turned the power settings to "High Performance", the high pitch was constant and severe.
So I disconnected my Nano Patch and went from the UR-44 directly to the monitors and the sound practically disappeared.
I am so relieved. I don't know why the Nano Patch caused the boost in this power related sound and I will contact them to find out.
I should have tested this long ago. I never thought a passive device would have the effect it did.

Did you try bolting a grounded piece of wire into the casing with a self tapping sheet metal screw. :-)
 
On serious note; It's possible that the case isn't acting as a shield. This could be for a variety of reasons including the possibility that the shield connections on the TRS or XLR isn't connected properly to earth at the I/O box or Speakers and so the shield cannot extend from the cabling to the Nano case as one might hope it would.
 
You can connect a grounded wire to the Nano chassis using one of the case screws and see if the whining noise subsides. This may cause a ground loop type buzz to appear and not be a useful solution but it will give you some clue as to what is happening, or it may actually solve the problem.
 
best regards,
mike

Hi Mike,
Am I connecting the ground wire between the computer case and the Nano Patch?  What gauge do you recommend?
 
Thanks.

I'd try any gauge that is convenient for you. 20awg or 18awg should work fine... if it's going to work.
 
I'd try connecting the Nano Patch case to the screw that holds the face plate of your AC wall outlet for starters. That takes the ground back as far is practical and if it helps then you can look for a ground connection (such as the computer case or something in your audio rack) that is more convenient.
 
 
Here's a image showing the grounded center screw:
 

 
Unfortunately the image also shows a 3 to 2 prong ground lift adapter (in it's intended application) and I want to make it clear that I didn't post the image to suggest the use of ground lift adapters. I posted the image because it shows the screw I mentioned above.
 
all the best,
mike
 
 

Thanks Mike.  Now were did I store that old wire....?