Hi all, I have been tinkering with (and using) a project I call BGAdaptor for a while now, and thought it might be of interest in this forum. Login to view image The BGAdaptor contains a small ESP32 microcontroller and a few extra components, that is disguised as a slightly larger-than-normal 7-pin DIN to 3.5 mm jack adaptor. It works with both Mozart and ASE-based products, and with Beogram turntables and CD players. Beocord tape decks are also supported (yeah, that was an after-thought, but I decided to keep using the BGAdaptor name ;)). The Data link source plugs into the DIN end, the jack goes into Line-in on a network connected Bang & Olufsen speaker. 
Inside the box, the ESP32 is wired to the Datalink pins where it can send and receive data signals, and at the same time it listens to the event stream from the speaker over WiFi. This means that I have bidirectional control between the speaker and Data Link source; select Line-in and the Beogram starts playing. Switch source and it stops. Standby switches it off. Setup and a control interface is available on a web page hosted by the adaptor itself, all local, no cloud. 

You can even hook it up to Home Assistant and expand functionality further :) Login to view image Here's an older video of some of the things you can do (the web interface has changed A LOT since):