This slight buzzing, which is usually only heard in silent moments and only in piano mode, is due to the fact that the sound has to be “looped through” the Bluetooth module.
Noise can be minimized if all cables leading to the Bluetooth module are first twisted together as shown in the installation video and instructions.
Note: The buzzing sound may be amplified when using memory cards other than our original ones, as some cards draw more current than others.