[. . . ] Dangerous high voltages are present which may result in electric shock. · To avoid risk of electronic shock or damage to the unit, do not permit any of this equipment to become damp or wet from water or drinks. If this does occur, immediately unplug the power wires and send the product to your local dealer or service center as soon as possible. [. . . ] Connect the remote terminal to the remote output of the head unit using 16 gauge (or heavier) wire. Connect an empty fuse holder within 18" (45 cm) of the car battery, and run 8 gauge (or heavier) cable from this fuse to the amplifier location. Then connect the fuse holder to the "BATT+" connection on the amplifier. 2. Make sure there is sufficient air circulation around the intended mounting location. Mark the location for the mounting hole screws by positioning the cabinet where you wish to install it. Thoroughly clean the area you plan to attach the subwoofer, using a vacuum cleaner. Then attach the supplied double adhesive tape, and put the subwoofer in the place and press down on it securely. BASS600 Amplified Subwoofer User's Manual - page 5 6. Connect all line inputs and outputs (if used) using high-quality cables. Set all level controls to minimum position, and set all crossover controls/switches to the desired frequency points. Then set the volume control on the head unit to about 3/4 volume, and adjust the subwoofer's input level controls to just below the level of distortion. Further fine tuning of the various controls may be necessary to obtain best results. Don't misuse the level control! Do not mistake the input level control for a volume control!It is designed ONLY to match the output level of your audio source to the input level of your subwoofer. Do not adjust this input level to maximum unless your input level requires it. Ignoring these instructions will result in an input overload to the amplifier in the subwoofer, and excessive audio distortion. [. . . ] Try to set the head unit as high as possible (without distortion) and the amp input level as low as possible. Check that the Input Level Control is set to match the signal level of the head unit. Check that the minimum speaker impedance for the amp model is correct. [. . . ]