I used a Converter Plug, you can buy these on Amazon or Ebay. On my Runblepack is a 100-220V compatible ac/dc adapter only the Plugs itself dosent fit. If yours also can handle up to 220V then you only need a simple Plug Converter for 3-5€. If its a 100/110V Only then you need the morr expensive and bigger ones that also convert 220v to 110V. You can see it on the Label on your Plug. But i think it will be the same for all Rumbles so a simple Plug Converter should be enough :).
Im also from germany but i thought i write in English that everyone can understand 🙂 if you have morr questions just send me a PM in German 🙂