3.5mm input interface with 4-pole jack connects to headset with microphone, compatible with mobile phones for voice calls; another terminal features a莲花 (RCA) interface. 7-band equalization circuit with ±12dB control range at frequencies 60Hz, 150Hz, 400Hz, 1kHz, 3kHz, 6.5kHz, and 15kHz, utilizing TI or ST TL074 components. Features 7-band sound equalizer pre-amplification with classic 4580 op amp providing 14dB gain. Input impedance: 20k ohms, output impedance: 600 ohms. Sound equalizer includes NE5532-based headphone amplifier circuit with 47-type driver design, suitable for driving various headphone types with adjustable high and low frequencies. Constructed from aluminum alloy for high strength, corrosion resistance, and stable performance. Operates on DC 5V–12V power supply. Dual-channel o output.