Issues with stereo volume

I purchased my Prius III last Saturday and for some reason, I think because the car had just gotten to the dealer and wasn't inputted in their system yet, they couldn't install my alarm at that time.

The sent someone to my house on Thursday to install the Karr alarm and it seems like ever since then my ipod and satellite are much louder than my AM. If I'm listening to AM, I have to have it up to around 20 but then when I switch to my ipod or satellite radio, it's very loud and I have to take it down to around an 8.

Is it possible that when installing the alarm the guy could've hit a wire or something that messed with the stereo or is it not even plausible? All of the work he did was near the emergency brake. I have the Nav unit if it makes any difference.