[. . . ] The use of a special red battery and ground wire RD-223, available separately, is recommended. The use of an improper fuse could result in overheating and smoke, damage to the product and injury, including burns. Check the connections of the power supply and speakers if the fuse of the separately sold battery wire or the amplifier fuse blows. [. . . ] Relationship between amplifier gain and head unit output power If amplifier gain is raised improperly, this will simply increase distortion, with little increase in power. Signal waveform when outputting at high volume using amplifier gain control Signal waveform distorted with high output, if you raise the gain of the amplifier the power changes only slightly. The female terminal can be connected to the auto-antenna relay control terminal. 1 Special red battery wire RD-223 (sold separately) After completing all other amplifier connections, finally connect the battery wire terminal of the amplifier to the positive (+) battery terminal. 2 Ground wire (Black) RD-223 (sold separately) Connect to metal body or chassis. 3 Car stereo with RCA output jacks (sold separately) 4 External output 5 Connecting wire with RCA pin plugs (sold separately) 6 Speaker input terminal Please see the following section for speaker connection instructions. To protect the wiring, wrap sections in contact with metal parts in adhesive tape. Never cut the insulation of the power supply to feed power to other equipment. Never ground speaker wire directly or band together multiple speakers' negative (*) lead wires. If the system remote control wire of the amplifier is connected to the power terminal via the ignition switch (12 V DC), the amplifier will remain on with the ignition whether the car stereo is on or off, which may exhaust battery if the engine is at rest or idling. Install and route the separately sold battery wire as far as possible from the speaker wires. Install and route the separately sold battery wire, ground wire, speaker wires and the amplifier as far away as possible from the antenna, antenna cable and tuner. Improper connection to the amplifier may result in malfunction or personal injury due to burns from overheating. For bridged mode for a two-channel amplifier, with a 4 W load, either wire two 8 W speakers in parallel, Left + and Right * (Diagram A) or use a single 4 W speaker. For other amplifiers, please follow the speaker output connection diagram for bridging shown on rear: two 8 W speakers in parallel for a 4 W load or a single 4 W speaker per channel. For any further enquiries, contact your local authorized Pioneer dealer or customer service. [. . . ] Insert the supplied tapping screws (4 mm × 18 mm) into the screw holes and push on the screws with a screwdriver so they make an imprint where the installation holes are to be located. 3 Install the amplifier with the use of supplied tapping screws (4 mm × 18 mm). To ensure proper heat dissipation of the amplifier, ensure the following during installation: -- Allow adequate space above the amplifier for proper ventilation. [. . . ]