The AAII-GM12 adapter is designed to be used with Monsoon systems that have either external CD player or XM (Note: the XM source is actually a separate receiver module inside the dash). The GM AAII-GM12 audio adapter easily hooks up by unplugging a connector at the back of the head unit (the connector that goes to the XM receiver and/or the external CD player), plugging the cable from the AAI-GM12 into that connector on the back of the head unit, and then plugging that cable connector that you just unplugged into the connector on the AAII-GM12.
So basically the GM adapter intercepts the stereo analog audio from the XM and/or Ext CD player, and injects your own external audio into the head unit. To use it, you turn your Monsoon stereo head unit to XM (or external CD if applicable), and then depending on the switch setting (i.e. the switch that comes with the GM adapter), you either listen to XM, or your own external audio! The adapter's switch is actually a 3 position switch --- to choose the source audio (i.e. XM and/or CD), or your own external audio 1 or external audio 2 (that's right, you can provide TWO different external audio sources to this thing!) No soldering!
For the person that asked me about installing the external audio jack into head unit... it's fairly easy. 1. Remove the head unit 2. remove the bottom cover. 3. look inside and you'll see an unused area on the head unit faceplate that you can drill a small hole, and mount your external audio jack into it 4. mount the jack 5. mount the GM adapter behind, or near the head unit, inside the dash 5. Put the head unit back in and Rock out!
I must say that I was a bit disappointed that the GM adapter's internal gain is not as high as it should be. In other words, when you go from radio or XM to your external audio, you'll notice that the external audio is not as loud... so you'll need to turn the volume on your external source audio up pretty high. I wish they'd designed a gain control inside that GM adapter, but alas they didn't..... Still, for the price and easy install, it's worth it.... and if you are able to feed a strong signal into your external audio jack it sounds really good!
Just to add --- If your stereo system does not have any external device connected to the head unit (e.g. XM receiver, external CD changer), then there is NO external audio feeding in to your head unit and your options for adding an external audio input are limited. IF your system has a working cassette player, then the BEST option for external audio is to use a cassette adapter (that thing that looks like a cassette but has an audio cable coming off of it). It actually sounds really good, much better than a real cassette (if the player's head is aligned right, that is). If no working cassette player, then next option is to use an FM modulator. They only sound as good as FM (and that's if it's a decent modulator and you can find a blank channel on your local FM). Otherwise your looking at either replacing the head unit or modifying the factory unit to add an external input and switch; this would require a schematic and knowledge of electronics circuitry.
Hope this helps.
