LIGHTWEIGHT AND PORTABLE: The Hi-Fi headphone amplifier features a portable and lightweight design with a sturdy aluminum alloy casing, perfect for enjoying music anytime, anywhere. WIDE COMPATIBILITY: This portable Hi-Fi headphone amplifier boasts wide compatibility and can be used with MP3 players, MP4 players, phones, music players, and many other devices. RECHARGEABLE BATTERY: The headphone amplifier has a 1500mAh rechargeable lithium battery that provides over 8 hours of use. There is a volume knob for adjusting the volume. HIGH PERFORMANCE: The Hi-Fi headphone amplifier supports most high-impedance headphones (16-300Ω), SNR>100Db, +N=0.0003%, allowing you to enjoy excellent sound. Two-Level Boost Switch: The portable Hi-Fi headphone amplifier features a two-level boost switch, enabling it to produce not only louder sound but also clearer, more realistic stereo sound without distortion.