Just to add another data point to the thread concerning how the original Music Port works, use of the Autotronic driver, etc, in case someone might find this helpful.
I installed my Music Port for the first time 2 days ago. After install was completed correctly, it's been running flawlessly ever since and is pretty much what I hope it would be. It's easy enough to navigate through my music folders on the PC server from the various Grand Concerto (GC) keypads, and the Mirage PC client that comes with the Autotronic software is fast & easy to use. I have had 3 channels of Pandora streaming for a couple days continuously without issue, I will probably go buy another minijack-to-RCA connector so I can stream 4 (requires 7.1 instead of 5.1 audio). The 7.1 Realtek 889 chipset that is built into my motherboard works great by the way.
After making all the hardware connections, I downloaded & installed the latest Autotronic MCS driver. I did not install anything that came from Nuvo.
I hit a couple problems/quirks during my install, but it mainly seemed specific to me as opposed to a flaw in the system. I couldn't understand why the MCS driver kept showing 2 channel audio only and I couldn't utilize the 5.1/7.1 audio. The issue was that I was working on the server via Remote Desktop which forced a standard Stereo output not driven by the Server's soundcard driver. Once I closed the session and worked on everything directly from the server, all audio operated as it should.
Another "airhead" moment was when I got the 5.1/7.1 showing up, but still couldn't get more than 1 channel showing on the GC keypads. This was simply forgetting to enable all sources for the keypads via the Nuvo Configurator software. When I originally installed the GC I had disabled all sources except the ones being used, and had since forgotten about that
Note: Once I was finished & everything was working... I found when I briefly lost internet connectivity (had to unplug the cable modem briefly while re-routing the cable), that even though other apps (email, browser, etc) had no issues restoring connectivity without a reboot, Pandora was hung & required a full reboot.
Final Note: I haven't had a chance to experiment with this to confirm but it seems like I needed to run Mirage once from the server after a reboot to get Pandora going before the GC keypads would then show Pandora as an option under "Radio".
Pandora: Never used it before until I got the Music Port installed. I love it!! I think my Grand Concerto will be nearly exclusively used for Pandora, and some playing of music albums on my PC.
That's everything in a nutshell.