OK, with that budget and that you want loud and clear music I presume you are going to amplify.
In that case I would recommend you get a dsp (digital signal processor) it gives you EQ and time alignment. Depending on the unit, EQ per channel, per driver, 16 band or 32 band or even parametric, 4 channel in 8 channel out some even 12 or 16out.
A dsp will be money better spent than a head unit (with your budget as they can work together but cost is a factor here) and it means you will have full midi screen, steering controls etc.
Sound deadening is often the most overlooked, more sound deadening the better the car will sound.
CLD tiles (aluminium foil with butyl backing) stop vibration and improve bass.
Closed cell foam and mass loaded vinyl block Road noise from outside.
Lots of brand, not worth spending lots if you don't have EQ to correct the sound in the environment or don't have deadening in but..
First question, are you wanting to run 2 way (mid bass and tweeter) or 3 way (mid bass, mid range and tweeter)?
Second, are you fitting them in factory position or planning to make/buy speaker pods
As for what what brand thats a bit harder and depends how much you want to spend.
A good quality amp will sound the same as any other good quality amp of the same class.
Do you want one or multiple? Where are you planning on fitting them? If space is an issue then one slightly larger amp might be better than multiple. Class d are usually smaller and cooler than AB for the same power output.
Do not buy an amp based on max power as manufacturers lie. Look at the fuse size and fuse size x voltage (14.4 max in a car) = max theoretical power. JL, audison, hertz, old soundstream, genesis, focal, dls, b2 audio list goes on and on are good quality amps to many to list.
Buy the correct size cable for the size of amp draw from your amplifier.
Don't buy CCA wire it's a con, spend the extra on OFC. If you want cheaper large diameter cable buy welding cable not as flexible but a lot cheaper and BS rated for oil and heat. See below pics for size needed.
Speaker cable I'm using 16awg for 75watt rms for the doors and tweeters. And 12awg for the subwoofer. All OFC.
Always use at the battery with the correct fuse for your max system draw.
Hope this gives you enough to get started.
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