Coil whine is unavoidable in devices with coils because electrical current triggers resonances and vibrations that can be heard acoustically. These noises can occur immediately or over time. They arise from natural, harmless wear and tear and are not covered by the warranty. Coil whine does not affect the function of the device and does not represent a material defect. There are no promises about this in product descriptions or advertising materials. Private customers can return products within 14 days of receipt without giving any reason.