This circuit is designed for use when audio equipment is connected to a power amplifier and the output sound level is low. It is suitable for small-signal audio amplification. Amplification gain: 8x (18 dB). Includes a USB charging cable. Not intended to drive headphones directly; designed to connect to external audio amplifiers. Compatible with standard mobile phone USB chargers. Battery life: up to 60–70 hours of continuous operation on a single charge. Features the classic dual op-amp NE5532, high-frequency electrolytic capacitors, and a noise-reduction circuit design—ensuring clean, quiet performance with no background noise and improved audio clarity. Input and output interfaces: 3.5 mm jack and RCA (phono) connectors. These two interface types are provided for flexibility across different setups; only one should be used at a time. Input options: RCA (L/R) and 3.5 mm jack. Output options: RCA (L/R), 3.5 mm jack, and headphone output. Includes an adjustable volume knob for precise level control. Compact and portable design. This is a preamplifier only—not a power amplifier—and cannot drive passive speakers directly. Broad compatibility with common audio sources: DVD players, CD players, set-top boxes, MP3 players, TVs, smartphones, computers, tablets, microphones, phono turntables, sound cards, guitars, bass guitars, electronic instruments, and game consoles. Compatible outputs include: powered speakers, subwoofers, Sound Blaster devices, reverberators, AV receivers, post-amplifiers, and headphones. Color: Black Material: Metal Package includes: 1 × Audio Preamplifier 1 × USB Charging Cable Note: Actual product color may vary slightly due to lighting conditions and screen settings. Dimensions may vary by ±1–3 cm.