Helpless with a 2010 Yaris sedan

[sqcomp]

I agree with the general opinion that you don't need to spend thousands for decent sound.

That being said, I'm probably the antethesis of the spirit of this thread. Still, you have many options available to accomplish your goals. I read that you've already replaced your speakers, yet they still sound crappy. You're thinking about a source unit. I'd seriously look into an amplifier as well. I can guarantee you that you're not going to get the advertised power claimed from the source unit...get some oomph to the speakers and see what you can do about properly tuning the system.