I have connected it to the car's internal USB. The Technical Data/FAQ also says: Our power supplies are equipped with two USB ports. This allows you to charge your phone or connect your navigation device at the same time when operating your Highway. See "
https://www.pure.com/de...". The angled plug is LINE-OUT (to the car radio), the straight plug is LINE-IN (music from the mobile/player). Operate Pure Highway together with Garmin GPS without interference.