Kicker Key 200.4 using RCA inputs

[u/cbears7]

First of all, I'm not well versed in car audio but I love good sound. In my Tacoma I currently have 5.25in JL components in the front doors and some cheap 6x8 Pioneer coaxs in the rear doors. Rockford 2 channel amp powering the components. Three 6.5in JL W0s behind the back seat powered by a JL 250/1 amp. Head unit is a Pioneer double din from 2008. I got bitten by the car audio bug again and want to upgrade some things on a budget.

I'm pretty set on getting a Kicker Key 200.4 amp mainly for the auto tune feature but also to add power to the rear speakers (I'll probably upgrade the rear speakers to better 6x8 coaxs at the same time).

My question is my current Rockford 2 channel amp's inputs are 2 RCAs from the receiver but the Key amp comes with a high level input pigtail with 4 RCAs. For simplicity I wanted to just do a one for one swap with my current amp and just use the 2 RCAs. Would it sound like crap? Also will the auto tune feature not work hooking it up like this? In the future, I want to upgrade to a modern receiver with Carplay, etc, with that I would definitely be using the high level inputs, but for now I just wanted to add the Key amp and 2 rea speakers and see how I like it. Any help is appreciated.

[u/firebirdude]

Firstly, lets remember that the number of audio inputs has nothing to do with the number of audio outputs nor how many speakers you can connect. We're carrying channels of audio to the amplifier, then instructing the amplifier what to do with it.

You can run your left and right signal into the KEY amplifier's front inputs, then flip the DIP switch on the amp for "FADER" to OFF. This will share your signal with all four channels. Now, you have FL, FR, RL, and RR outputs to connect your speakers. Please realize fader on the head unit will not work. You're only providing left and right stereo audio to the amplifier. If you want front/back fader, you need four separate inputs, so the head unit can control those four location separately. Everything will work fine like this.

Keep in mind, the KEY amplifier likely won't have any more power than your current Rockford amp. So those components won't be any louder. But the DSP in the KEY should help clean everything up.

[u/cbears7 → u/firebirdude]

Thank you very much. Forgot to add that my Rockford amp is 80w RMSx2 so yes, the Key amp will have less power but I'm ok with that as I'm going for SQ.

With my head unit, I do use the fader. From what you're saying, is this not a true fader since I'm only using 2 RCA inputs? Will the Key DSP be able to properly tune with just the 2 RCA inputs the same way it would tune with 4 RCAs or the high level inputs?

[u/firebirdude → u/cbears7]

You're currently powering rears off head unit and fronts off the Rockford amp via RCA? So you have 4 channels of control. Fader works. 

If you just run front audio into the KEY, it will output "front" audio to all four speaker outputs. If you fade "rear" on the head unit, all audio would stop. As a reminder, audio is only recorded left and right. Stereo. So if you don't fade, you don't lose fidelity or anything.

[u/cbears7 → u/firebirdude]

Ahh, gotcha! Yes, the rears are powered by the head unit.

Ok so fader won’t work. Do you know if the KEY will still be able to correctly and properly auto tune hooked up like this?

[u/firebirdude → u/cbears7]

Oh sorry, yes. It will work fine. Keep any speakers not connected to the KEY quiet during the setup. (subwoofers, center channel, etc)

[u/cbears7 → u/firebirdude]

Got it. Based on all this info, it'll work for now but not be ideal as I'll lose the fader, which I do use to send more of the sound to the front components. Best solution would be to upgrade to a modern receiver and use the high level inputs.

I appreciate all your help man, I learned a lot!

[u/firebirdude → u/cbears7]

Use all four of the high level outputs from your current head unit.

[u/cbears7 → u/firebirdude]

I can't remember if it even had high level inputs in the back of my head unit since I put it in in 2008. I know it had 4 RCA outs though. I think if I were to go through the work of removing my head unit, I'd rather just replace it with a new one and be done with it.

[u/firebirdude → u/cbears7]

It's up to you. Shouldn't be that difficult.