Looking for an inexpensive solution to improve upon the Bose Premium in my brand new (less than 200 miles) Black Touring MDX, I decided to replace the four door speakers with Infinity 652I speakers. I'm not handy so I decided to purchase/install the speakers at a nearby Circuit City. However, the Audio Manager refused to change the speakers, citing the impedance mismatch - which he said might make worsen the sound - or even damage the headunit. Is damage to the headunit a possibility? Thanks for any advice.