JBL MS-BassPro SQ Owner's Manual page 4

If your car audio system's head unit has a line-level subwoofer
output:
If the head unit has a line-level subwoofer output, you can connect it to
L. Front
Speaker
L. Rear
Speaker
Single RCA Audio Cable
(not supplied)
Use Either
Connector
4
Audio System
Head Unit
Subwoofer
Output
If your car audio system's head unit does not have line-level
outputs:
R. Front
IMPORTANT: Some factory-installed audio system amplifiers include
Speaker
performance. To get the most bass possible from your MS-BassPro SQ,
R. Rear
Speaker
insert the speaker wires into the holes on the back of the adapter. Tighten
the set screws to secure the wires.
Loosen
Screws
IMPORTANT:
other. Touching wires can cause a short circuit that can damage the head
unit or the subwoofer.
connectors.
Insert Tighten
Wires Screws