"The make-or-break part is the front speakers. If you have a fixed budget, the front speakers are where you should not cut any corners."
"The most important aspect of any installation is the tuning, time alignment and equalization. Without good tuning, alignment etc, the best most expensive equipment can be made to sound horrible."
"The absolute key to a good installation is the installation. No matter how good the equipment is, a bad installation will make it worthless. Bad Speaker location, bad connections, bad grounds, poor quality wires, bad voltage regulation, all these will cause more harm than the good that comes from investing in high quality components."
"The single most effective thing you can do to improve your listening experience is to bypass the poor digital/analog converters that rob you of so much sound quality before the sound even reaches the speakers."
These are not exact quotes but a decent representation of the variety of advices from seasoned professionals, audiophiles, experts, or people perceived as such because let's face it they do know a million times more than both Average Me and my friend Average Joe combined.
So of course one weak link in the strongest chain will cause it to fail, but we can't all become end-to-end audiophile electrical and electronic experts just so our cars don't sound crap. After a decent amount of reading I could conclude that there is no point in starting because I will need to learn the finer points of Speaker construction, advanced electrical and electronic theory and design, wave theory, fluid dynamics, mechanical properties of materials and more before I can even consider buying the strict minimum of fibreglass construction material, high quality speakers and crossovers, a few amps, a couple of processors, soundproofing material and some anti-depressants.
So if anyone with experience and global understanding could put this in perspective, it would be much appreciated.