my 06 mcs has the H/K stereo with the amp and the ipod adapter. my problem is that when listening to the ipod the music will not get anywhere near as loud as it will get when listening to the radio or a cd.

not a big deal till i get on the freeway with the windows and sunroof open and can not hear the music anymore.

anyone else noticed this or know how to correct it?

 

Could just be the base volume on your ipod - I'd try that first.
I know the Aux-in has a separate volume, IIRC accessed by pressing the music symbol repeatedly.