Usage Tips:Feature:1. [Unique Design] Unique power switch button design is very easy to use. You can enjoy high quality music with headphones through the 3.5mm headphone output, and the RCA line output and AUX headphone output can be output at the same time.2. [Multi Compatible] Compatible with most low volume sound sources such as phones, TVs, MP3 players, portable CD players, computers, video games, etc. and boosts their output to the level needed to drive amplifiers or speakers.3. [HiFi Sound] NE5532 op amp with pluggable socket design, easy to replace other op amps to enjoy different sounds, bringing a lot of DIY fun for audiophiles. High quality sealed potentiometer, wide frequency band, excellent dynamic response.4. [Compact And Durable] Compact shape, exquisite appearance, compact all metal design, durable, can block electronic equipment from electromagnetic interference and noise suppression. Natural sound, warm and delicate, ultra low distortion.5. [Wide Application] Perfect size and functional design for home stereo systems, console or speaker setups, karaoke, recording, parties, live stage events and many other scenarios to increase output levels.Specification:Item Type: Headphone AmplifierMaterial: Aluminum AlloyColor: BlackWorking Voltage: DC 5-19VInput and Output: 3.5mm Headphone and RCA Lotus InterfaceAmplifier Chip: Dual Op Amp NE5532Parameter: 1. Can directly drive headphones, but it is not recommended to use with the output of the amplifier2. When your device is connected to a small power amplifier can use this circuit, suitable for sound small signal amplification3.10 times amplification, that is, 20db.Package List:1 x Amplifier