MSI KT4M-L Manual page 76

4-Channel Mode for 4-Speaker Output
When this mode is selected, plug the two front speakers to the Line
Out connector on the back panel, and the other two rear speakers to
the Line Out connector on the S-Bracket.
Refer to the following diagram and caption for the function of each
phonejack on the back panel and S-Bracket when 4-Channel mode
is selected.
Select "Default Phonejack"
1 MIC
2 Line In
3 Line Out (Front channels)
4 Optical SPDIF jack
5 Coaxial SPDIF jack
6 Line Out (Reserved for Center
and Subwoofer channel, but it
is not functioning here)
7 Line Out (Rear channels)
Back Panel
1
2
4
3
Using 4- or 6-Channel Audio Function
Deselect "Default Phonejack"
1 MIC
2 Rear Speaker Out (Rear channels)
3 Line Out (Front channels)
4 Optical SPDIF jack
5 Coaxial SPDIF jack
6 Line Out (Reserved for Center and
Subwoofer channel, but it is not
functioning here)
7 Line Out (Rear channels)
S-Bracket
6
5
7
A-7