This circuit uses three TI NE5532 operational amplifiers, with one stage for gain, one stage for buffering, and one stage for equalization processing. It is equipped with a mute circuit for power on/off, which basically eliminates impact noise during power up and down. Reverse connection protection for positive and negative power supply poles is provided. It features wide voltage regulation and can operate within DC9-29V. A built-in boost module can convert a single power supply into a ±14.5V dual power supply to power the circuit, offering a large sound dynamic range and strong driving force, capable of driving high-power rear stages. The output is designed with two impedance interfaces for easy connection to different power amplifiers. The low-impedance interface can be connected to pure rear-stage power amplifiers. The high-impedance interface can be directly connected in parallel to the line input terminals of combined power amplifiers with preamps or other audio devices. Static Power Consumption: Approximately 1W Frequency Response: 20Hz-20kHz Amplification Gain: 14dB Tone Adjustment Range: ±15dB Input Impedance: 50kΩ High-Impedance Output Impedance: 10kΩ, Output Amplitude: 0.7Vrms Low-Impedance Output Impedance: 600Ω, Output Amplitude: 3.5Vrms Bluetooth Reception Version: 5.3 Supports: U disk/TF card/LINE input Player Supported Formats: MP3/WMA/WAV/APE/FLAC FM Radio Support: 87.5MHz-108MHz Power Supply: 2 x AAA batteries(Not included batteries) Color: Black Material: Plastic+Metal Package Contents: 1 * Tone board 1 * remote control Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.