Adopting QCC3008 Bluetooth chip supports APTX-LL lossless transmission, CM6642 decoding chip supports 24bit/192KHz and compatible with Windows/Mac/Linux system, 5NE5532 op amp provides better performance and wide sound field, classical analog 47 headphone amp architecture can drive 32-300O headphones. Perfect Design & Attractive Appearance: with treble and bass control to enjoy more smooth and delicate sound. Fashionable CNC machined black aluminum alloy chassis combined with warm light from vintage tube looks amazing, very suitable for the customers who pursue wonderful auditory and visual enjoyment. Notice: PC-USB input is compatible with Windows/Mac/Linux system, also supports OTG function but Android system needs OTG cable and IOS system needs large current camera kit, please prepare by yourself. This is a tube preamp which needs to be connected with an amplifier or active speakers, cannot drive passive speaker directly.And it is not a phono preamp, cannot work with turntables. The headphone jack output is prior, stereo RCA output will auto disconnected when connecting headphones to its 3.5mm output. 1N Tube - 1Power Adapter - 1USB Cable - 1Bluetooth Antenna - 1User Manual. Usually it cost about 35USD-50USD. If you receive defective item, please kindly notify us within 14 days. This item is in the category "Consumer Electronics\TV, Video & Home Audio\Home Audio\Receivers & Amplifiers\Amplifiers & Preamps". The seller is "topskyrc" and is located in this country: CN. This item can be shipped worldwide.