Newbie wants to learn the best 'Original' aftermarket audio system for BRZ
 

By original I mean works with the OEM unit signal input and hopefully power supply so I do not have to run wires through the firewall to the car battery.

Pls advise! Thanks a lot!

For just a head unit, there is no need to run any wires through the firewall. With the exception of the overhead microphone (the factory mic doesn't seem to play nice with anything other than the OEM HU) all of the power and speaker connections are present in the dash and usable by most any aftermarket HU. The easiest thing to do is buy from Crutchfield and pay the extra few dollars for them to supply a plug-and-play wiring harness. No cutting of factory wiring and you can return to stock in about 10 minutes if you want.

If you want to install an additional amp for a sub-woofer then you will likely need to run a cable to the battery.

It sounds like you mean a subwoofer amp not a head unit.

Any amp even the optional factory subwoofer will still require you to run thicker power cable to the battery.

This is not as hard as it sounds. It just takes time. Look up YouTube vids on amp installs.
Buying a plug and play kit makes it easier and faster to install.

Thanks I think I will need the headunit and also a multi channel amp to power a set of new speakers replacing the factory speakers.
From my understanding there is a factory amp as well. I would like to use its power supply for the aftermarket amp if possible. Any recommendations?

yup 100% correct!
Any set you recommend?
Hopefully using the factory amp's power source.

I would recommend strongly against this. Any aftermarket amp you will likely get is going to require more power than the factory amp's wiring is designed to carry. While I understand the desire to try and just use what's already there, this is one of those times where upgrading the wiring is going to be necessary. If you don't want to run new wires, then honestly you don't want a new amp either.

There is a factory two channel amplifier in the trunk that powers the door speakers only. It does not produce a lot of power and the 12 volt circuit that supplies this amplifier is fused at 15 amps. Which means that the wiring itself is not heavy enough to carry a lot more. If you want to improve on the factory amplifier using the stock wiring your new amplifier will need to be fused at no more than 15 amps. One workable alternative is an Alpine KTP-445U.

Here is a link to it

Here is a link to another thread about re-using the trunk amp wiring.

Thanks a lot!

Thank you for your input!

FYI: Another post explaining more about how the factory system is wired.

A lot of people seem to like the OEM Audio Plus kit. I think it wires right up to the factory system with no modification.

you can't use that power supply for anything other than the stock amp.

yes, the oem plus is a good option, but it still requires wiring through the firewall. @8:00 in this video:

https://youtu.be/nMDDobyihyc


there are absolutely zero options to add an amp and not run power wiring.

Again no amp, factory or aftermarket amp will use the factory door amp power.

As for the kit, All depends on how much money you want to spend.

For $200 you can get a basic sub/amp combo. It's not sound super loud, but it will give you that bass bump you'll looking for.

For a basic system, you'll need at lest 150-200 watt amp and a sub that can match the power.

Heck you can get it at Walmart, $80 amp, $80 sub/with box, and a $40 wiring kit.
Or get an all in one kit sub, box with built in amp.

It's a total DIY you can do in about 3-4 hours.

Okay guys, I'm not understanding this. Maybe we are nit-picking over technicalities, but there is a 12 volt DC supply circuit fused at 15 amps available at the factory amplifier location along with ground and speaker level input and output wiring. No, you should not try to run both the factory amp and an additional amp on that 15 amp circuit. No, you can't run a great honking sub-woofer amp on that 15 amp circuit. But, the Alpine KTP-445U (and similar units from other vendors) is rated at 45 watts x 4 channels or can be bridged for 90 watts x 2 channels all while requiring no more than a 15 amp 12 volt supply circuit. I'm guessing the factory amp produces something around 30 watts x 2. Going to 45 watts per channel on the doors really isn't an upgrade but 90 per channel would be noticeable. Or, how about getting a dual voice coil subwoofer and sending 45 x 2 to the doors and 45 x 2 to the subwoofer? The sub isn't going to be (obnoxiously) loud but it would certainly fill out the bottom end.

Would I do this myself? No, I ran 4 gauge from the battery to the sub amp in the trunk. But as long as the OP understands the limitations with this implementation I think it would work. Thoughts?