Mini Bluetooth 5.0 Tube Preamp Speaker Receiver Stereo Pre-Amplifier Usb Player. Warm Tips U-disk input is prior to Bluetooth, Bluetooth will auto disconnect when U-disk is inserted. Parameters Audio input: Bluetooth 5.0/USB(U-disk)/Stereo RCA Audio output: Stereo RCA Maximum capacity U-disk supported: 64G Highest sampling rate U-disk supported: 24Bit/192K (FAT32) Formats U-disk supported: MP3/APE/ FLAC /WAV/ WMA Treble / bass range: 6dB Frequency response: 20Hz-20kHz(1dB) Distortion: ?0.03% RCA input sensitivity: 0dBFS/1V SNR: ?100dB Working voltage: DC 12V Dimensions(W*D*H): 97*118*33mm/3.82*4.65*1.30in Package Dimensions(W*D*H): 250*215*65mm/9.84*8.46*2.56in Net Weight: 337g/0.74lb Package Weight: 700g/1.54lb Packing List 1*P6-MINI Preamp 2*6A2 Tube 1*DC12V Power Adapter 1*Bluetooth Antenna 1*User Manual Multiple audio inputs for different requirements: support Bluetooth 5.0 / USB(U-disk) / Stereo RCA connections, perfectly match with phonoes, TV, tablet, projectors, computers etc., support U-disk to play APE/ FLAC /WAV/ WMA lossless formats besides MP3; greatly improve the sound quality for your amplifier or active speaker. HIFI warm sound and replaceable tube design: default 6A2 tube to filter out the digital feelings and soften the sound to be warmer and sweeter, full and mellow with large dynamic; pluggable tube design, can be upgraded to 6*1N / JAN5725W / 6AK5 / EF95 for tube shaping and rolling and enjoy different sound styles. Separate tone control and input switch: besides main volume control knob, also with independent treble and bass knob to present amazing music with rousing highs and deep lows; with input selector and LED indicator, easy to switch input channel and show its working state, no need to plug cables again and again. Compact size and attractive appearance: CNC machined black aluminum alloy chassis, sturdy and durable; decorated with warm orange light from vintage tube looks great, provide different acoustic enjoyment even in limited space, very suitable for the audiophiles who pursue wonderful auditory and visual enjoyment.