Is it also possible to connect the MDT via the 1611 converter (hence via ML) and thus allowing it to be part of a larger ML system like a BS3000 could form part of?
Yes, that should work but haven't tested that in detail yet. I know that I could control a BC9500 + 1611 via ML. I guess audio then need to be injected via the video sources.
Or where do you “enable” the MDT to decide which ML products it will turn on when streaming to it?
Currently two scenarios are implemented. N.Radio/N.Music provider source center" and BL3500/BL2000 stand-alone.
The first sends a virtual N.Radio key to the audio master once a stream is playing. Only the audio master will be switched on then.
The second one simulates an audio master. Once you start a stream a virtual "radio" key is sent to the "broadcast" address all linkrooms are listening to. So if you connect more than once BL3500 in that setup most likely all will switch on - but only tested with one so far.
So in a link system you really want to use the source-center mode. It will behave similar as if you would hook up a BeoMedia 1, BeoPort or BeoSound 5 to your BS3000. By changing the address of the virtual N.Radio key you can change which device is being switched on automatically.
If this is true and one would only chose BS3000 to turn on by the MDT, can the other link speakers still join and play the same source as and when you chose “N.MUSIC” from the Beo4 in a link room?
Sure, the join command always works. In theory one could also run multiple instances of the AirPlay emulator each tied to a different ML address. While only once source can play at the same time you could use that for automatic switch-on of different ML devices.