OK, did you really disconnect every cable from Balance, except the headphones and USB connection?
Are the headphones passive? (Not connected to a power source)
Can you actually hear that same rising feedback sound in those headphones, when everything else except USB is disconnected?
I'm at a loss right now, have never heard of an issue like this.
If you have access to another computer, please test the Balance device there to see if it sounds better, which would mean the issue is somehow local to your computer. (maybe some kind of power supply / USB power issue somehow?)
If it is really coming from Balance itself, it would be even more strange if it was not like that from the beginning, but started sounding like that suddenly.
It would be best if you create a e-mail support case.
Start here: https://www.propellerheads.se/compan...balancesupport
(The point of disconnecting everything for this test is to make sure Balance is only electrically coupled to a single AC power source (the computer), which would eliminate ground loop interference as a cause.)