I'm not an audiophile (not even close) so all I have is factory speakers and a $50 amp. I couldn't believe how good this unit sounds.

[soapbox]
Now, if you really want to be impressed... get a subwoofer! I recommend a single 10" in a sealed box. I know you won't believe me, and no amount of talking will convince you of this, but a subwoofer will make an even bigger improvement in your sound than the RioCar did.
[/soapbox]

tanstaafl.