I do not understand why I need an external wall wart (which has a ac/dc converter built in anyway). The linked ac/dc converter module should also be capable of doing what the wall wart is doing, or not? Here is the english page: https://secure.reichelt.com/ch/en/snt-module-30-w-15-v-2-a-screw-irm-30-15st-p157873.html?CCOUNTRY=459&LANGUAGE=de&GROUPID=7242&START=0&OFFSET=50&SID=92db537754100a6141611bb670db0080e2c7e59f22f5f154bb995&LANGUAGE=EN&&r=1
If possible I would like to avoid having two external power sources.