Pioneer GM-2000A Owner's Manual page 4

Connect the components correctly as shown in the diagram.
Test-connect all components before securing them into place.
Test-operate your entire car stereo system to ensure that there are
no faulty wiring connections between this unit and the rest of
your Car stereo system.
The input selector of this amplifier functions automatically.
Therefore, the amplifier may be used with either a Pioneer car
stereo with DIN sockets or a car stereo with RCA pin jacks. For
information about connecting a stereo, see the section entitled
"When combined with a car stereo with DIN sockets" or that
entitled "When combined with a car stereo with RCA pin jacks".
When two channels (stereo) are used, the speakers should have a
minimum rating of 100 W or more. When a single channel
(mono) is used, the speaker should have a minimum rating of 200
W or more. If a speaker whose rating is below that recommend-
ed is used, the speaker may be damaged. The impedance of the
speakers should be between 2 and 8 ohm.
For detailed information concerning connections between differ-
ent components and this unit consult their respective instruction
manuals and follow those recommendations precisely.
When wiring connecting leads into place secure them with clam-
pers and adhesive electrician's tape. Additionally, to prevent any
damage to the insulative coating of the connecting leads, protect
them with adhesive electrician's tape wherever they may come
into contact with any sharp edges.