Mein De’Longhi Wasserkocher ist sehr laut. Was kann ich machen?

All kettles regardless of manufacture will make a noise whilst boiling. The noise level is determined by the power rating, the body material and the shape. A 3KW kettle in stainless steel will always have a noisier operation than a low power plastic type. Your kettle will get noisier as it reaches boiling point. Once your kettle has boiled the noise will abate. If your kettle is older, descaling the kettle may reduce the noise.