Product Highlights: 1: Adopt all-aluminum shell, because the electronic tube will heat when working, the aluminum shell can facilitate heat dissipation.2: Built-in switching power supply booster circuit, fully isolated power supply, low noise.3: Adopt electronic tube for audio pre-amplification, and triode for post-amplification A. The sound quality is high fidelity, and the sound field is obviously improved.4: A large number of imported ruby ??audio capacitors, German imported Weimar WIMA capacitors, all copper foot precision 1% metal film resistance5: Built-in lithium battery power supply, or direct charger power supply, the charger has a perfect charging protection circuit.6: Adopt all-copper gold-plated shielded 3.5 earphone holder, with low contact resistance. Sound quality is guaranteed.7: The imported electronic tube is adopted, and the sound quality is superior to the general domestic electronic tube.8: The power filter capacitor uses Japanese ruby, ELNA capacitor, quality assurance.9: Built-in large-capacity lithium battery, working time is about 4 hours.10: Military-grade FR-4 double-sided fiberboard and gold plate are used, and the conductive resistance is small when installing components.12: Fashionable appearance, with small size, easy to carry, the gospel of headphone enthusiasts, removable tube amplifier in the sense.13: Large dynamic, improve the frequency response of the sound field, enhance the driving force of the headset, can easily drive 16-600 Euro headphones. It can also be used as preamp for other power amplifiers. Instructions for use 1. Headphone jack: The standard 3.5 stereo headphone jack is compatible with 99% of the 3.5 stereo headphone on the market. If you use 6.35 headphone jack, you need to purchase an adapter jack separately The headphone output impedance defaults to 16-80 Euro, if you need to connect high-impedance headphones, you need to contact customer service or leave a message2. Power switch: The switch is designed to toggle up and down, dial down to shut down, and dial up to boot. It needs to be turned off when charging, otherwise the charging time will be prolonged, or the battery will not be fully charged.3. Power indicator: There is an LED indicator on the power switch. When using the built-in battery, the green light will turn on when the power is turned on, and turn off when the power is turned off. If the charger is plugged in, both the power on and off lights up in red, prompting the user that the charger has been plugged into the amp.4. Volume adjustment: The volume increases clockwise, and the volume decreases counterclockwise. Please turn down the volume before turning it on, and increase the volume according to the sense of the motherboard after turning it on, so as not to damage the ear hearing or damage the headphones5. Audio source input: The audio source can be connected to mobile phones, tablets, computers, mobile players, CD players, etc. Please use the corresponding audio cable to connect. Charging instructions 1. When the power indicator flashes on the amp, it means the battery is low and needs to be charged. Lithium batteries have no memory effect and do not need to wait for the battery to run out before charging.2. Shut down and charge as much as possible to ensure that the battery is fully charged.3. The indicator light above the charger is red when charging, and the indicator light of the charger turns green when fully charged.