@Emil Sorry for the slow reply... There's a few things to look at. Wiim publishes a RESTful api as seen in the first PDF. Under the hood, it's built on an Arylic platform, which has further available RESTful endpoints.

https://www.wiimhome.com/pdf/HTTP API for WiiM Products.pdf https://developer.arylic.com/httpapi/#device-connection-status

It also presents a general UPnP, self documenting SOAP style API at http://<device-ip>:49152/description.xml. The UPnP spec is what dictates the SUBSCRIBE verb.

One quirk of the Wiim REST API is that it defaults to https with a self signed cert, that Flic doesn't seem to like. To get it to work with Flic, you have to run a proxy (e.g. http > https)