Please school me on car audio. (1 Viewer)


Oct 19, 2016
Toronto, ON
I've finally decided to tackle the stereo system on my truck, and i've discovered that my knowledge in this department is seriously lacking. There is no "car audio" section on mud, so hopefully there are some experts here in the 80-section that can help me figure this out.

My truck (1996) has the factory "9 speaker" sound system. I bought new head unit (Kenwood DDX-9907XR).
I will be replacing the 2 dash speakers, 2 front door speakers, 2 rear door speakers and the factory sub. I will not be using the rear roof speakers.

So here are my questions:
1) In factory configuration, dash and front door speakers run off the same wires from the factory amp. The door speakers i want to use are rated 50W RMS each, and the dash speakers i want to use are rated 25W RMS. Lets say i get an aftermarket amp that outputs 75W RMS per channel and connect it to original wiring that will feed both the door and the dash speaker. Will it split the 75W to the dash/door speakers equally (37.5W each), potentially blowing the smaller dash speaker at full volume?

2) Is it possible to limit the output of the amplifier to specific channels? For example - 75W RMS to front two channels, but only 25W RMS to rear channels (to avoid blowing much smaller, rear door speakers)

3) The head unit outputs 4x22W RMS and has 5V pre-amp outs. Does it supply signal to BOTH amplified and non-amplified outs simultaneously? If so, would it be possible to run the front dash speakers off the head unit, rear door speakers off the other two HU amplified channels, and then hook up a 4 channel amplifier to the non-amplified output on the HU? Then use 2 channels on the amp for the front door speakers, and then bridge the other 2 channels and use that for the small (6-8") sub in the rear?

4) I want to use the smallest possible amplifier and mount it in the stock location, completely out of sight. I never owned a vehicle with aftermarket amplifier. If i wire everything like i described in #3 above, will i be able to control all the volume of the system with JUST the master volume button on the head unit? In other words, i dont want to EVER mess with the the controls/adjustments on the amplifier. Is this possible?
Last edited:


M Go Blue
Aug 18, 2003
Nashville, TN
I would eliminate the two dash speakers. Those are not going to add to the quality of the overall sound and eliminating them will certainly simplify the installation and operation. With only the four door speakers you can completely control the output of the system using the left/right balance and front/rear fader controls on the head unit. Unless you are some kind of headbanger type the built in amplifier in the head unit will most likely meet your needs. You can always add an amplifier at a later time. Instead of the dash speakers add in a powered subwoofer. Most modern head units have a subwoofer output and builtin adjustments to control output levels.

That said if you choose to use the dash speakers not only the wattage of the speakers, the impedance, efficiency and differences in the direction they point will all come into play. The front dash and door speakers are setup in parallel in the OEM configuration which will divide the impedance the amplifier in half. Where the rear door speakers will still have higher impedance making adjustments to compensate for the differences much more complex. You would have to connect each speaker separately to a multi-channel external amp (six channel) or multiple smaller amps. Your cost to accomplish this is going to escalate from $$$ to $$$$.

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