[SM#80]

I will preface this post with that fact that, while I do enjoy the sounds of a good stereo, I am not well versed in the details or technical language of high end audio systems.

So,

I am looking at purchasing an '09 E92. It is a very low optioned car (which is fine), but it does not have the one option I would like, which is the premium sound package. My question to those in the know is, what would it take to upgrade the standard stereo package in the M3 to something more robust? I am guessing that just replacing the existing speakers wouldn't suffice and I would need to add an amp and possibly a subwoofer. I am not looking for a system that you can hear from blocks away, but one that has crisp highs and a nice low end.

Any help/direction/advice would be appreciated.