Upgraded headphone amplifierThis high fidelity headphone amplifier supports impedance of 16-150 , compact, small and portable, easy to carry, and can output excellent sound quality without distortion.3.5mm auxiliary input and outputHigh quality audio suitable for your mobile phone MP3 MP4 laptopNoise reduction function, enhanced dynamic distortion, perfect pure stereo effect, optimized high-definition voice and music sound qualityAluminum matte surface, stylish and compact designNot only suitable for music enthusiasts, but may also be an ideal gift for people with hearing difficulties.TroubleshootingQ: Why is there a buzzing/hissing sound?A: Please do not use it during charging as it may cause current interference. That's why there is noise. After fully charging, please disconnect the power and use the headphone amplifier.Q: Why is this amplifier not high enough for my large headphones?Answer: This headphone amplifier supports headphones with an impedance of 16-150 ohms. Please check the impedance of the headphones.Mini HiFi Earphone Amplifier: Exquisite, compact, lightweight, portable, easy to carry3.5mm AUX input and output, with a signal-to-noise ratio>120 decibels and THD+N 0.0003%, not only produces louder and more realistic stereo sound without distortion.[Aluminum Matte Surface] The fashionable design provides you with a comfortable handheld feeling, while the aluminum matte surface makes it durable Wide and Compact It is significantly compatible with various digital devices, such as MP3, MP4, mobile phones, and computers. (Note: It is not recommended to use it during charging as it may cause current interference and noise.)Input/output port: 3.5mm audio portDistortion rate: 0.004%Signal to noise ratio: 120dBLoad impedance: 16-150 Power output: 250mW, impedance 16 Ampere internal voltage: 4VCharging voltage: 5V DCFrequency response: 20Hz-20kHz ( 3dB)Lithium battery capacity: 1000mAhAmplifier usage time: approximately 6-8 hours