I've been disturbed for years by the supposition that: I can get the highest quality audio components in existance, but if the source sucks, it's all worthless. Is this unfounded? And how does it translate to "high quality" in-car mp3 audio?

Do you guys with perfect sound systems (tanstaafl, etc) get high quality out of your empeg?

Is it just a matter of using high bitrates and great encoders?

Most importantly, what if the underlying CD is low-quality for ANY number of reasons? (analog recording, bad mix-down, clipping, bad compression, just too darn quiet all around, etc) I honestly think that a bunch of my major-label commercial CDs just sound sub-par.

Bottom line is, before I go researching high quality in car audio and spending plenty of money to get a great system, will it all be undermined by me playing mp3 through it or undermined by poorly done CDs?
And since most of my MP3s are 128 and 160, I guess I have to give up my dreams of good in-car audio (since I don't want to re-rip again), but what kind of equipment would you recommend to make it at least sound good?

Thanks.