KMA 24 H - 71 pinout
1 - Spkr Gnd
A - Aircraft Gnd
2 - Voice Rec
B - PA Speaker
3 - Com 1 mic audio
C - Com 1 mic key
4 - Cockpit Speaker
D - Pilot headphone
5 - Com 3 mic audio
E - Com 2 mic audio
6 - Com 5 mic audio
F - Com 4 mic audio
7 - Spkr Pwr (3A breaker)
H - Com 2 mic key
8 - PA Mute
J - Com 3 mic key
9 - Com 4 mic key
K - Com 5 mic key
10 - Unswitched unmuted audio
L - ADF audio
11 - (key slot)
M - (key slot)
12 - Marker audio
N - DME audio
13 - Nav 2 audio
P - Nav 1 audio
14 - Unswitched audio
R - Com 5 audio
15 - Com 4 audio
S - Com 3 audio
16 - Com 2 audio
T - Com 1 audio
17 - Instrument lighting Gnd
U - 28V lights hi (or) 14V lights Gnd
18 - 14V lighting hi
V - Key enable/disable
19 - Mic 1 key
W - ICS key
20 - Mic 2 / ICS 2 audio
X - Mic 2 key
21 - Isolate
Y - Private
22 - ICS 3 audio
Z - Mic 1 / ICS 1 audio
23 - ICS 4 audio
a - ICS 5 audio
24 - Isolate 2
b - Copilot headphone
25 - 14/28V headphone Pwr (1A bkr)
c - Gnd
A lot of the "private" and "isolate" is there for dual installations and muting passengers done through a separate toggle switch.
King expects 2 circuit breakers, 1 for "headphones"(1A) and one for "speaker amp"(3A)