BMW E46/4 HK Amplifier
8-channel HK Amplifier

So I took apart my stock stereo amp. I was amazed that it's actually a true 8 channel amp although the non-HK system uses a 10 channel amplifier. Each speaker in the car is individually driven by its own amplifier except for the front door tweeter and midrange are passively crossedover. The HK system does have another amplifier mounted to the subwoofer assembly.
BMW 65.12-06 920 996 01
E46/4

The amp uses four stereo single chip amplifiers by NXP, TDA8563Q 2x40W (into 2 Ohms). Each chip is has two independant amplifiers inside. I have arbitrarily numbered then #1-4 in the picture below.

 

 

Amplifier Connections for HK system. Located in the rear left side of the trunk

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+ (HLV&MLV) 0.5 Yellow/Red
34 HLV-, Left Front Tweeter- 0.5 Yellow/Brown
40 MLV+, Left Front Mid-Range+ (HLV&MLV) 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+ (HRV&MRV) 0.5 Blue/Black
12 HRV-, Right Front Tweeter- 0.5 Blue/Brown
42 MRV+, Right Front Mid-Range+ (HRV&MRV) 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
7 SUB_ON, (X18774-2) 0.5 WS
19 TAA, Speedometer Signal (X18774-7) 0.35 SW/GN
20 TAA, Speedometer Signal to instrument cluster  
6 SUB_IN+, Out+ to subwoofer amp (X18774-1) 0.5 GN
14 SUB_IN-, Out- to subwoofer amp (X18774-6) 0.5 BL/GN
15 RKL, Spacial Sound Button  

The amp uses four stereo single chip amplifiers by NXP, TDA8563Q 2x40W into 2 Ohms, but, more realistically it's more like 20 Watts per channel into 3 Ohms.

HLV and MLV are wired together and are coming off the amplifier chip #2 left
TLV is coming off the amplifier chip #3 left
MTHL is coming off the amplifier chip #1 left
LH is coming off the amplifier chip #4 left

HRV and MRV are wired together and are coming off the amplifier chip #2 right
TRV is coming off the amplifer chip #3 right
MTHR is coming off the amplifier chip #1 right
RH is coming off the amplifer chip #4 right