Bass and mids started cutting out with stock radio (standard radio, not Bose). Replaced with Pioneer unit and have same problem. Speakers all playing, but they all sound like tweeters. No low end or mids at all. Please no responses about how little bass the stock system has or something like that. Had this car for over two years and know what the speakers sound like. It's gone from decent sound to sounding like headphones (that are laying somewhere, not on your head).