Note: This is a preamplifier, not a power amplifier or phono preamplifier, and cannot be used for passive speakers. Specification: Item Type: Tube Preamplifier_x000D_Material: Aluminium Alloy_x000D_Distortion: 0.03%_x000D_SNR: 100dB_x000D_Frequency Response: 1.5dB (20hz-20khz)_x000D_Input Interface: RCA_x000D_Output Connector: RCA_x000D_Operation: Toggle Switch, Volume Adjustment Knob, High and Low Pitch Knob_x000D_Applicable Devices: For Mobile Phones, Computers, Tablets, Tvs, Set-top Boxes, Projectors and Other Devices with Analogue Output Devices, etc._x000D_Power Adapter Specification: US Plug 100-240V Features: 1CLEAR SOUND QUALITY: This HiFi preamplifier with low noise integrated circuits and high quality components to remove low frequency noise ensure clear sound quality. 2COMPATIBLE: RCA input for preamplifiers to computers, CDs, telephones etc. and RCA output to digital amplifiers, active multimedia sound devices with lossless sound (excluding RCA cables). 3SAFETY DESIGN: This preamplifier has a built in switch, circuit shock protection and overheating protection for a long life. 4PRACTICAL: This tube preamplifier improves all the detail, transparency, immediacy, richness and tone associated with your music. 5APPLICABLE DEVICES: The vacuum tube preamp suitable for mobile phones, computers, tablets, TVs, set?top boxes, projectors, etc. PackageList: 1 x Preamplifier 2 x Electronic Tube 1 x Chinese and English Manual 1 x Power Adapter