Conclusion: sheer fraud, a higher quality device would pay for itself very quickly.
Addendum: Due to the exorbitant power consumption I tried to cancel the purchase at the seller, DastroMedia. Since the statutory cancellation period for all tests was but unfortunately passed by just two days, I was shown there the cold shoulder. Goodwill is a foreign word at DastroMedia. But the lack still be under warranty, so I turned then on the official form to the manufacturer Amica. There you have the request then simply completely ignored. Conclusion: I'm staying right on the power-hungry.