Hi Luke, 

Started to think about another solution if you interact with the MacMini via bluetooth ;)

Check this bluetooth player from loudlink that is fully controllable via datalink, I've been thinking to purchase that one for my units that handle datalink. This one I think can be interesting also with alexa or google home to link the bluetooth to the loudlink so that the sound automatically start up your BS7000 when you ask to play a song. 

link

link

Maybe another option can be an old Beoport / Beolink PC2 connected to your mac and using the old BM-Link software for Mac OS:

http://www.odlund.se/bmlink/

It's from a Beoworld member as far as I know and I don't know if it still works but it could be worth a try as it does exactly what you want.

Another option would be to connect a Playmaker instead of the Airport express. With that option you can use your Beo 4 to skip tracks on iTunes as far as I remember.

Thanks everyone for some really interesting options - not all of them will work for what I need but there are a couple of interesting avenues there if I can't get this to work with the 1614 converter (as per Ralph's suggestion) which I'm awaiting delivery of.

Just to give a clearer picture of what I'm trying to achieve, I need a solution that will allow remote control of the Mac Mini from all my link rooms in a reasonably large master link network (2 beovisions, an MLGW, 4 beolink passives, 2 beolink actives, and the Beosystem 7000 connected via a 1611 converter) across my house and summerhouse/shed.

I live in a 1920s built house and all of the walls are solid brick, so long cable runs are a nightmare of drilling and chasing which I'm trying desperately to avoid. I previously ran a bunch of cables under the floor, but have recently had new parquet flooring fitted throughout the downstairs so this is no longer an option! Stefan is absolutely right that a really simple option would be to run data and ground from the 1611 already attached to the Beosystem through to the intronic box attached to the mac mini (which lives in a server rack in a cupboard under the stairs), and this is my backup plan if I can't get the 1614 to work: It will involve drilling trough 2 brick walls and chasing some cable runs so at the moment I'm trying my best to take advantage of the existing Masterlink installation. 

I'm not sure why I never managed to get my Beolink PC2 (since sold) to work: I tried it with BMLink but it was completely unresponsive to commands on the network, although I was able to control it locally with an attached IR receiver. As TWG says it may be because I'm running the most recent Mac OS, although I have heard others have had some success with it. The only other potential benefit of using the Lintronic in this set up is the additional flexibility it brings in terms of my home automation system - I run and Indigo server on the Mac, so there is potential to do more interesting things than just controlling iTunes if I get it working right.

I really appreciate the time and effort people have gone to with all the suggestions so far - I'll let you know how the 1614 works out when it arrives. If that fails I'm taking Stefan's advice and firing up the SDS drill!

All the best

Luke