In my 83 i have installed a (wow, forgot the name of the stereo..lol) for question purposes i shall call it a jvc as im not dressed and dont want to go outside just yet, its a cd/mp3 player, which im pretty sure is a little deeper than a reg cd player as i have to really shove it to get it in the hole, anyways, after about an hour of driving it sounds like the speakers are blown but only on cd mode, radio sounds fine... so, is my stereo too big and the cooling fins not getting adequate airflow, or should i be looking elsewhere??? anyone else have this issue???

 

Maybe you can pull it out a bit, and let it run for the same amount of time and see if it still happens?