Sharepoint social.feed Authorization

I'm currently testing RESTfull API access to Office365 Sharepoint server using bearer authentication (oAuth2).

I can succesfully get current files in the OneDrive via the /_api/web endpoint but get System.UnauthorizedAccessException on _/api/social.feed endpoints.

I granted all Sharepoint rights to the (test) application, just to be on the safe side: MyFiles.Write MyFiles.Read AllSites.FullControl AllSites.Manage AllSites.Write AllSites.Read

What am I doing wrong to retrieve the social.feed(/my/feed) for the access_token I'm presenting?