Mazda Ipod Integration Kit is wimpy

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2012 Mazda5 Touring
Just bought a 2012 Mazda5 Touring edition microvan with the audio package that has the 6 disc cd changer and Sirius radio. Had the dealer put on one of those ipod integration kits that fits in the glove box. Very disappointed with the sound, it is very wimpy, does not compare with dynamic range or volume that comes out of other audio sources. Not even worth listening to. I had the dealer look at the problem and they told me that that is the way it is. I can not believe that they would design it that way. I have no technical understanding of the connection in the back of the radio, but someone must have set it up the wrong way or forgot to do something. Wondering if anyone knows what might be wrong or if you have experienced this issue.
 
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