Brawl

Hey guys, first off I just got my 07 touring Z about 3 months ago and have loved every minute of it. Now for my question, I bought the USA spec for the iPod, and when I was installing it into the back of the headunit (stock bose) I noticed that there was a plug in where the sat/cd changer was supposed to be (I thought there was not supposed to be a plug there)... Now maybe I missed something but I dont have xm and its the 6 cd changer built in... So I was just wondering if someone knew what it was that was plugged in? The 6cd changer still works and the ipod sounds so much better, so its not that big of a deal, but I would just like to know what it is i left unplugged haha.

Thanks in advance,
Justin