Problem rear door speaker wire color and polarity

Hello, I own a ds4 Opera e-tense from 2023, but unfortunately without a focal system. I would like to install an active subwoofer under the seat to improve acoustics. I should connect to the rear speakers, without disassembling the door panels intercepting the wires that pass under the rear sill. It would be enough for me to know with certainty the right color and polarity of these wires. I hope someone can help me, it would be appreciated.

I am attaching 2 photos of the intercepted wires under the sill of the rear doors.
Unfortunately I think they are not the right ones.

Volume level (output level) to the rear speakers are in my opinion very low and i assume that it’s also cut-down in terms of low frequencies. I would recommend to check that first, test it with fader in EQ settings of the car and maybe install on Your phone an app - some sound spectrum analyzer to check this at least with phone microphone - which isn’t that bad at all.
Then You may compare if low end frequencies are the same if You put the phone at front and rear woofer however stock woofer in front is 130mm and rear is 165mm coaxial speaker.

I have changed the speakers in front (tweeters and woofers) and rear (to coaxial) and rear speakers just play but without anything special and very low volume in comparision to the front.
I have installed Morel Maximo Ultra HE speakers in front and rear which have very high efficiency - around 92-94dB.

I think that without any good amplifier You won’t achieve anything significant without turning up the GAIN with risk of clipping if You take the signal from the rear speakers which may destroy Your subwoofer.

I’m waiting for connectors (they aren’t available yet anywhere) to be able to take from the headunit front and rear HI-LEVEL signals, then put it into 4 or 5 channel amp so that the subwoofer will be driven with signal from front speakers (full low-end frequnecies) not from the rear which i think is cut-off from low frequencies and has low volume overall.

I would suggest to take signal for the subwoofer from front speakers since rear speakers have roll-off in bass frequencies (below 200Hz)

Rear Right electrical frequency response:

Front Righ electrical frequency response:

Best option is to install addtional amplifier, sum signals from left front and right front and drive the sub with that - pure signal using additional low-pass filter.