I've had my mk5 astra for about 2 years now, ever since i got it i've been wanting to play music from my iphone throught the stereo.
However, i have the CD30 MP3 with no aux input!!
I've been searching for so long to get this sorted and have come across so many threads relating to this, all suggest that there is no solution but to upgrade your head unit.
Since i have the multi function display with the board computer i didn't want to take this route as i would lose functionality.
I'd just about given up hope when i found a solution!
Just thought i'd post this here as it is maybe the answer to lots of peoples problems.
All you need to do is buy one of these:
and one of these:
it uses SOT (Sound on top) and doesn't require any tech2 etc.
If the volume on your iPod is above 30% it mutes the standard audio source.
Hope this helps!