Originally Posted by brian
.... I'm big into Premier head units, the immense control you have over sound quality and EQ is hard to beat, they have some pretty awesome DSP built in....
Pioneer has dropped the Premier line of equipment. The replacement, Stage 4, is ridiculously expensive given what the OP has so far said about sound system goals.
Speakers: Listen at a local shop. Barring that read a bizillion posts on DIYmobileaudio.com and synthesize your own opinion of the many presented there. Re: listen at a local shop. The main purpose of the sound board, for me, was to judge mid-bass clarity and the overall "brightness" of the tweeters. That is (IMO) more or less independent of the board mounting. To the OP, why you should go listen, and why I said brightness, is that some speaker companies tend to use tweeters that, on the good side play every nuance of the music, but on the bad side can sound overly harsh or bright -- they tend to be metal domed tweeters. Others, using something like a silk dome tweeter, are not as clear but not as harsh/bright -- all depends on your preference. Then again there are other types like ring radiators (higher end Alpine) that are a good between mix, but if mounted in the stock locations causes problems (the tweeters lose sound when not pointed toward the listener - more technically said, off-axis performance drops off significantly). Confusing? That's why basically, you have to go listen and see what you like/dislike.
Head-units: I have owned Pioneer Premier, "regular" Pioneer, Alpine, Kenwood, and JVC (currently have Pioneer X930BT). More money generally gives you more bells and whistles, but not much difference in sound quality. Virtually all of them have RCA out cables that run to an amp and they are have a very flat frequency response (something not true of many OEM factory head-units). I suggest picking the unit more on what features you like and the user interface that appeals.
Amps: I personally have tended to acquire medium to higher end units over the years (JL Audio, Xtant, Premier - currently have JL Audio), but honestly given enough power and a good install, they are pretty much indistinguishable.
Wires/cable: One of the biggest rip-offs in the audio world. Given adequate construction (strength, appearance), only three things define wire/cable: resistance, capacitance, and inductance. If a manufacturer tries to sell based on any other thing other than this I suggest their marketing is stronger than their engineering.