I've been trying to retrofit the Harmon Kardon audio upgrade into my 2009 MCS with the then-available HiFi audio upgrade. The final piece of the puzzle was the HK amplifier, which I put in a few days ago.

With the HiFi amp, the new HK speakers sounded pretty good. But with the new HK amp, everything is *waaaaaaay* too bass-y and my car's gong (when you first start the car or don't have your seatbelt on) is incredibly loud. I just had a 2010 dealer loaner car with the HK audio upgrade this past weekend, so I know what it's supposed to sound like … something with mine is wrong.

What I'd like to do is check to see if the HK amplifier I have is bad by either hooking up a known good HK amp in my car, or hooking up my HK amp in another car with a known good HK system in it.

Are there any R56 owners with the new HK audio upgrade in the Tucson, AZ area who might be willing to help?