It won’t play to your stereo, just plays through the speakers…but the stereo can adjust the volume (and I think the Parrot device can do volume adjustments as well)…the system basically plugs into your audio system between the stereo and power and stereo and speakers so it integrates into the flow of power and sound through the system…it doesn’t interact with the stereo in the sense, nothing is sent to the stereo for the stereo to do…
It is a very good system and pretty easy to install (assuming you can easily access the back of the stereo and cables)…once installed it is very neat and dead easy to use.
Might be a bit more than you want to spend but once you have it you will be wondering why you didn’t do it before – it’s not the sort of thing you take your mates to your car to show but it just makes things so simple once done.