you will always need amps for crisp sound, i have never run across a headunit that will send enough power out to really bring out the sounds.

i have a 1k watt amp running my front and rear components by power acoustik, and it sounds pretty damned good. probably 300 dollars there, my head unit plays dvds/mp3s/cds, also by power acoustik, about 250 dollars, its not the best and it leaves room for improvement, but it does what i need it to do. i spent 600 on subs and amp, 2 12" woofers and a 3k watt amp, way overkill, but i like to crank it sometimes.

so a basic shopping list

4 channel amp of around 5-600 watts should be plenty for some clarity

a small monoblock amp with a small ported box for a 10" woofer

a headunit you can live with to play mp3s