The second connector for sure is for the speakers wiring.
Usually the blues go to the Mids, and the yellow is for the tweeters.


Just off the top of my head - I had to resolder my whole setup after a disaster with a failed Eonon install, since I have the DSP amp

Someone a little more knowlegeable will help me out on this, I'm sure...

__________________
----------------------------------------------------------------
2006 X5 4.8iS (facelift) in Imolarot + Ivory leather & alcantara headliner
1999 E46 323i in Imolarot II + Grey nappa
1990 E30 320iSE Sterlingsilber