So I didn't read all of your thread but it appears you go it all sorted. 
A factory EWD would have been insightful from the beginning for you.
I installed an aftermarket amplifier in place of the oem unit but in my LC not LX. I'm sure it would have been the same or similar wiring. This provided me a pure low level signal for the aftermarket amp. Some splicing and custom RCA ends was all that was needed.
The only issue I had was that the factory head unit supplied a momentary mute signal to the amplifier to prevent "power on/off thump." Nearly all aftermarket amplifiers only have power ON thump mutes built in, not power off mutes or connectivity of a separate mute signal. When I would turn off the system, I would get a thump through all of the speakers...not a good thing long term for the speakers. It would have taken more engineering to solve the issue but by no means would have it been impossible or that difficult.
To address the comments about the head unit being the key to system I strongly disagree. Amplification of the signal is the best way to improve any audio system. Great speakers can sound like s*** on poor amplification and s***ty speakers can actually sound fair on a good signal. Anyone who thinks otherwise has been feed the bimbo best buy audio installer kool-aid.
I have since broke down and bought a cheesy aftermarket head unit for the simplicity of the usb connectivity. Other than the improved ability to adjust crossover points and levels, the sound isn't dramatically different than the stock head unit on an aftermarket amp.
A factory EWD would have been insightful from the beginning for you.
I installed an aftermarket amplifier in place of the oem unit but in my LC not LX. I'm sure it would have been the same or similar wiring. This provided me a pure low level signal for the aftermarket amp. Some splicing and custom RCA ends was all that was needed.
The only issue I had was that the factory head unit supplied a momentary mute signal to the amplifier to prevent "power on/off thump." Nearly all aftermarket amplifiers only have power ON thump mutes built in, not power off mutes or connectivity of a separate mute signal. When I would turn off the system, I would get a thump through all of the speakers...not a good thing long term for the speakers. It would have taken more engineering to solve the issue but by no means would have it been impossible or that difficult.
To address the comments about the head unit being the key to system I strongly disagree. Amplification of the signal is the best way to improve any audio system. Great speakers can sound like s*** on poor amplification and s***ty speakers can actually sound fair on a good signal. Anyone who thinks otherwise has been feed the bimbo best buy audio installer kool-aid.
I have since broke down and bought a cheesy aftermarket head unit for the simplicity of the usb connectivity. Other than the improved ability to adjust crossover points and levels, the sound isn't dramatically different than the stock head unit on an aftermarket amp.
