[. . . ] When the unit is used in the ACC ON position without turning the engine ON, it depletes the battery. There is a Protection function installed in the unit to protect the unit and speakers from various problems. To prevent damage to the machine, take the following precautions: · Be sure the unit is connected to a 12V DC power supply with a negative ground connection. Do not install the unit in a spot exposed to direct sunlight or excessive heat or humidity. [. . . ] Set to this position and make bridged connections to use as a high-power monaural amplifier. When the FILTER switch is set to the HPF (High-Pass Filter) or LPF (Low-Pass Filter) position, the threshold frequency can be adjusted with this control. This unit is equipped with a protection function for protecting this unit and your speakers from various accidents or problems that can occur. When the protection function is triggered, the Power indicator goes off and the amplifier stops operating. When the unit malfunctions and a DC signal is sent to the speaker output. When a ground wire of the center unit (cassette receiver, CD receiver, etc. ) or this unit is not connected to a metal part serving as an electrical ground passing electricity to the battery's negative terminal. If the Power indicator does not light when the power is turned on, the protection function may be activated. If you can't find the specified capacity fuse at your store etc. When using an RCA cable with a ground lead attached, connect the ground lead to this terminal. When you wish to use the unit as a stereo amplifier, stereo connections are used. the speakers to be connected should have an impedance of 2 or greater. When multiple speakers are to be connected, ensure that the combined impedance is 2 or greater for each channel. When you wish to use the unit as a highoutput monaural amplifier, bridged connections are used. When multiple speakers are to be connected, ensure that the combined impedance is 4 or greater. The genuine-accessory car stereo shall have a maximum power output of no more than 40 W. Do not connect the speaker output leads from a power amplifier (Optional) to the speaker level input terminals of this unit, for this may cause malfunction or damage. Do not connect cables and leads to both RCA cable input jacks and the speaker level input terminals simultaneously, for this may cause malfunction or damage. Connect the power control lead to a power supply which can be turned ON/OFF by the ignition key switch (ACC line). With this connection, shock noise may be generated when the power of the genuine-accessory car stereo is switched ON/OFF. [. . . ] Prepare commercially-available coil and capacitor with the closest ratings to the results calculated from the formula above. 25 (µF) and the coil rating should be as close as possible to 5. If you wish to bridge-connect a speaker, the speaker impedance must be no less than 4 ohms. Connecting a speaker with an impedance lower than 4 ohms may damage the unit. [. . . ]