Here is what I have learned since receiving my 2820 yesterday.
I don't care about stereo or mono right now, just trying to get audio as advertised.
Using a bluetooth headset to make cell phone calls works great. MP3 audio sounds good with BT headset connected. There is no XM audio with a BT headset connected. Not even on any type of audio speaker connected to the audio out jack on the 2820, or any other jack on the power cable or anywhere else on the 2820.
With a wired set of earbuds connected to the 2820 audio out jack and the Garmin microphone connected to the mic jack on the 2820 a BT phone call can take place and XM and MP3 audio works. However, the audio quality is horrible compared to a BT headset. No engine running or not even connected to a vehicle.
This is the rub, this cable arrangement will not work with intercom systems. There must be an adapter such as Autocom makes that has 2 male plugs at the GPS end and 1 male at the intercom end with probably a mixer in between. I would suspect that this setup would have all kinds of noise without GLI's installed. And even then probably still some static getting through. Hell there is even a low hum without the engine running or if connected to an AC outlet only.
Why is this product marketed as bluetooth, gps, mp3, and xm but these features do not all work together. This is not the result of too many hardware options to comply with. A simple correction in the 2820 circuitry or software would separate these signals correctly. So can someone explain why Garmin chose to allow mp3 audio but not xm? And please don't say it's bandwidth. After the signal is received in can be transmitted at a level that could match mp3 quality.
What I really can't believe is that the members of this forum as well as ADVrider, will berate BMW for final drives, wobbles, clutches and so on but find it completely acceptable to purchase a Garmin unit that will only perform partially as advertised. As BHO says, " That is fundamentally unsound"
So, if I'm wrong and the 2820 does EVERYTHING Garmin says it will do for you, not just partial performance that is "all you need", I would still love to hear from you.
Heck, after 3 calls to XM my unit still will not receive navtraffic and navweather signals. All other stations are fine.
Most of these problems are documented here and there on the net, but I can never find truly final solutions. I can't believe that many of us will just say "oh well, I guess I just won't use that feature, even though I paid good money for it."
I'm really looking forward to some of your responses/experiences.