BMW E46 10-channel HIFI Amplifier

So I took apart my stock stereo amp. I was amazed that it's actually a true 10 channel amp. Each speaker in the car is individually driven by its own amplifier and actively crossed-over. There are no passive crossovers anywhere.
BMW 8 368 230

Here is the inside with the cover removed.

The Amp uses five stereo single chip amplifiers. Three of the TDA7375, 2x35W (into 4 Ohms) amplifiers and two of the TDA8563Q, 2x40W (into 2 Ohms) amplifiers.

Front Tweeters - 35 Watts (4 Ohms)
Front Midrange - 35 Watts (4 Ohms)
Front Woofer - 40 Watts (2 Ohms)
Rear Door Midrange - 35 Watts (4 Ohms)
Rear Deck Woofer - 40 Watts (2 Ohms)

After doing a lot of bench testing and reverse engineering I have figured out most of the amp.
The front channels have a high pass filter at the differential to single ended input circuit which limits the low end to 23.6 Hz with a -6dB/octave slope. This is good in a way, it eliminates the low low end which the speakers can't reproduce anyway which will make it easier on the amplifier chips and lower overall distortion. The front woofer outputs goes from 23.6 Hz imposed by the input filter all the way up to 430 Hz. At 430Hz the fall off is -12dB/octave. For eq'ing the designers added two notch filters on the woofer output channel. One notch filter is at 190 Hz and the other is at 550 Hz. The 550 Hz notch is after the 430 Hz low pass filter which makes the roll off even steeper than -12dB/octave. Next is the mid-range output. It goes from 1.25 kHz to 5.35 kHz with -12dB/octave slopes on both ends. Notice that the woofer starts rolling off at 430 Hz, but, the midrange doesn't start coming in until 1.25kHz. There is a 820 Hz hole in there. Ok, now the tweeters. They start at 6kHz with a -12dB/octave slope. The components in this filter were not chosen for flat response. For some reason therefore there is a 0.5 dB bump just above the 6kHz crossover point. Again there is a hole between the two outputs. Midrange rolls off at 5.25kHz, but, the tweeter doesn't start until 6kHz. In the plot below I have normallized the outputs so they appear


Amplifier Connections for 10 speaker system (not HK)

X605 Description Wire Size and Color
5 Fuse 41 - 30A 2.5 RT/GN
38 RADLV+, Left Front Input+ 0.75 Yellow/Red
30 RADLV-, Left Front Input- 0.75 Brown/OR
9 RADRV+, Right Front Input+ 0.75 Blue/Red
17 RADRV-, Right Front Input- 0.75 Brown/OR
37 RADLH+, Left Rear Input+ 0.75 Yellow/Black
29 RADLH-, Left Rear Input- 0.75 Brown/OR
8 RADRH+, Right Rear Input+ 0.75 Blue/White
16 RADRH- Right Rear Input- 0.75 Brown/OR
26 GROUND 2.5 Brown
10 ANTENNA 0.5 White
33 HLV+, Left Front Tweeter+ 0.5 Yellow/Red
34 HLV-, Left Front Tweeter- 0.5 Yellow/Brown
40 MLV+, Left Front Mid-Range+ 0.5 White
39 MLV-, Left Front Mid-Range- 0.5 Blue/White
4 TLV+, Left Front+ 1.5 Blue/White
3 TLV-, Left Front- 1.5 Blue/Brown
31 MTHL+, Left Mid-Range+ 0.5 Yellow/Black
32 MTHL-, Left Mid-Range- 0.5 Yellow/Brown
2 LH+, Left Rear+ 1.5 Yellow
1 LH-, Left Rear- 1.5 Brown
11 HRV+, Right Front Tweeter+ 0.5 Blue/Black
12 HRV-, Right Front Tweeter- 0.5 Blue/Brown
42 MRV+, Right Front Mid-Range+ 0.5 Green
41 MRV-, Right Front Mid-Range- 0.5 Blue/Green
23 TRV+, Right Front+ 1.5 Blue/Red
22 TRV-, Right Front- 1.5 Blue/Brown
13 MTHR+, Right Mid-Range+ 0.5 Yellow
21 MTHR-, Right Mid-Range- 0.5 Blue/Yellow
25 RH+, Right Rear+ 1.5 Blue
24 RH-, Right Rear- 1.5 Brown

HLV and MLV are coming off the amplifier chip to the far left (TDA7375)
TLV and LH are coming off the amplifier chip 2nd from the left (TDA8563Q)
MTHL & MTHR are coming off the amplifier chip in the middle (TDA7375)
RH & TRV are coming off the amplifer chip 2nd from the right (TDA8563Q)
MRV and HRV are coming off the amplifier chip on the far right (TDA7375)