Hi Matt,
Apologies for the delayed reply to your PMs.
I can understanding your linking for the Symphony 1. You'll be pleased to know that it does not suffer from the same issue as the single-DIN Generation 1 stereos, so is a much more reliable piece of kit.
It does not, however, have any CAN bus implementation at all. As such, fitting it into a later model car (especially one with DIS) becomes more challenging.
Generation 1 stereos send information to the DIS display using a proprietary 3-wire interface rather than the industry standard CAN interface. As such, early A2 instrument clusters have connections for this proprietary 3-wire interface. I do not know whether this functionality was axed on later instrument clusters; I've simply never investigated this.
Lots of people have asked me to fit later CAN-enabled stereos to their early A2, but I've never been asked to fit an earlier stereo to a later A2. I can certainly make the Symphony 1 switch on and off with the ignition and I can make the button illumination logic work properly, but it may be that later DIS screens can only display information fed over CAN. I'll have to do some digging.
Edit: Some digging done. It appears the proprietary connections are still there on later clusters, but I don't know yet whether they're enabled in the cluster's software. A trial fitment would need to be done to be sure.
Cheers,
Tom