Some Q&A from a related thread, copied here for completeness:
Thanks again for the thread, it brought a few thoughts to mind and may very well be the approach I take. Do you mind a couple of questions?
Is there a reason you did the interface behind the head unit rather than at the amp, which I think is easier to get at?
I originally started with an adapter cable which claimed to be for an 04-06 SRX, whose Nav/radio wiring is identical to ours. That cable turned out to be seriously incorrect. I rewired it to work, and at that point discovered that any connection between the radio and cd did not override the cd output. Also, I needed to pull the radio out to place the parrot box behind (and now alongside) the radio.
Did you consider using the mute and the OnStar audio in rather than breaking into the music audio lines? Is it important to you to maintain the OnStar?
I thought about it, but looking at all the connections it appeared that the Class II network bus was involved in too much of this. I had the onstar trial active at the time and had not yet decided if I wanted to keep it (As in, might they offer a good deal to not let it lapse.).
For what it's worth, even being directly wired into the cd-to-amp connections, the incoming Onstar marketing calls overrode my music.
I thought that the Parrot output was for speaker level signals, not line level. Did this create any problems? Did you attenuate the signal any? Was there enough volume?
For whatever reason, it works fine. Setting the Parrot volume to about 70% of its scale yields the same volume as the car radio so switching between Parrot and radio/cd I don't have to change the car's volume setting. I expected to have to work on an impedence match but it was not necessary. I'm not an audiophile but it sounds fine to me. (Anyone coming to central Florida, PM me and we'll arrange a listening.)
I am not really wanting to mount another unit and am wanting to do commands and such either thru voice or on the phone. Will the Parrot let you do this?
Parrot accepts commands through its own microphone. I have a very basic cell phone and have never tried to use its voice recognition. You probably need to ask Parrot.
One thing I am considering is just hard wiring the phone in. I usually connect the power anyway. The hard part with that is getting the interrupt working so that if listening to a CD and a call comes in.
That's exactly how this setup works. The Parrot is its own mute box, so if you are not using the phone and not playing music, the regular radio and cd work normally. On an incoming call or access to the phone book, the radio/cd audio is shut off and the parrot audio goes to the amp. Note that if a music source is connected to the parrot when you start the car, you will need to press the parrot's pause button to switch it off so you can listen to the radio/cd.
