Answer to SLED. Ferrite beads are used to stop unwanted RF radiation from causing noise in cables, this does not appear to be RF noise it is noise passing between the laptop and the H90 via the 5V/ground. I can recreate the noise but simply connecting the outer metal of the USB C connector to the outer metal of the USBC socket i.e. without connecting the center conductor.
Inside a standard USB cable there are four conductors: red (5V), black (ground), white (data-) and green (data+). The key is that the 5V line coming from the computer is usually “dirty”, with superimposed spurious noises caused by the equipment itself and its peripherals. This dirt connects to the audio system, generating hums, hisses, or interference that sometimes vary depending on the processor load or even the fan speed.
This phenomenon is not exclusive to any particular brand: sooner or later, many users will end up experiencing it. The truly frustrating thing is that it ruins the experience and quality., especially in recording, live or critical monitoring environments where hum is no longer acceptable.
In addition, there is an aggravating factor: some noises increase when touching metal parts, strings, or even the floor, depending on how the masses are referenced. If the system “notices” your body, it can vary the level of humidity., something that fits with the typical 50/60 Hz and its harmonics when there are ground loops or potential differences between equipment.
In my humble opinion, the H90 should isolate itself from the USB Power supply. Since the H90 does not need USB power as it’s powered independently. All the H90 needs to do is pass the USB data stream and not allow any of the USB noise to get anywhere near the audio paths within the H90. This makes me think this is a bad design flaw. If I were them I’d get the blue tooth connection working to windows asap.
