Feature: 1. Portable headphone amplifier with four stereo 1/4 inch and four 1/8 inch headphone outputs. 2. Stereo 1/4 inch and 1/8 inch jack and RCA stereo inputs(wired in parallel) can be connected to any line-level audio source. 3. Built-in high quality potentiometers for each channel volume control. 4. DC 5V power supply, can be powered by USB power adapter, power bank or computer USB port. 5. With Stereo/Mono switch for selecting stereo or mono signal to be sent to the output channels. Specification: Features: Portable headphone amplifier with four stereo 1/4 inch and four 1/8 inch headphone outputs. Stereo 1/4 inch and 1/8 inch jack and RCA stereo inputs(wired in parallel) can be connected to any line-level audio source. Built-in high quality potentiometers for each channel volume control. DC 5V power supply, can be powered by USB power adapter, power bank or computer USB port. With Stereo/Mono switch for selecting stereo or mono signal to be sent to the output channels. Compact size and full metal shell design, easy to carry around and durable to use. Specifications: Model: AHA04 Material: Metal Color: Black Input Connector: stereo 1/8 inch TRS jack, Stereo 1/4 inch TRS jack, RCA stereo connector Input Impedance: 22K ohm Max. Input Level: +22dB Output Connectors: stereo 1/8 inch TRS jack, Stereo 1/4 inch TRS jack Output Impedance: min. 16 ohm Max. Gain: 20dB/channel S/N Ratio: >98dB Frequency Response: 20Hz-20KHz THD:< 0.01% Power Supply: DC 5V, >=1000mA via USB power adaptor Item Size: 11.3 * 7.3 * 5.9cm/ 4.4 * 2.9 * 2.3in Item Weight: 375g/ 13.2oz Package List: 1 * Amplifier 1 * USB Cable 1 * User Manual (English) Package List: 1 * Amplifier 1 * USB Cable 1 * User Manual (English)