When using Bluetooth or RCA input, ensure the volume is not too low to avoid automatic mute after 1 minute. Recommended external audio source volume is at least 60%. For startup, plug the 24V adapter into the power supply and connect the DC head to the product only after the adapter light turns on. Using other power supplies may damage the product. If the adapter indicator does not light up, do not connect it. Before use, ensure the switch is off and the main volume is not at maximum. Connect all cables, attach the antenna, and then connect the power supply. Turn on the switch to activate the power LED for normal use. This product supports only 24V DC power supply; other voltages may cause malfunctions. Bass and treble can be fine-tuned, with maximum right twist returning to original frequency response. Suitable for passive speakers only. Origin: China. Condition: New.