Adopt classical tube 6N3 design T8 is a tube headphone Preamp, which uses MAX9722 headphone amp chip, and 6N3 tubes can get warm and smoother sound, tubes can be replaced with GE5657,396A,2c51,12BA4,5670,6H3n etc,. You can change the tube according to your needs to achieve different sound quality effects The tube must be fully inserted during use! Multi-function switch knob Rotate the red knob to adjust the volume according to your preferences; Press the knob to control the machine switch ON or OFF;when the headset and RCA output are connected at the same time,you can double click the button to switch to the sate of simultaneout output of the headset and RCA(Headset output Priority) Exquisite and unique design The visual OLED digital display is more intuitive and clear, and the operation is more simple and convenient; T8 is custom-made, unique, exquisite, and desktop, It is designed for everyone who loves HiFi, audiophiles and beginners. 6N3 Digital Tube Preamplifier Tube Headphone Amp Preamp PC-USB supports sampling rate: 192KHz(And is compatible with W10/MAC/XP System) Distortion: RCA: 0.2%/HP: 0.003% SNR: RCA,108dB; HP, 106dB Working voltage: DC12V Maximum output power: RCA: 1.9V/HP: 120mW@32Ω Input sensitivity: 2V Net weight: 0.87kg Frequency response: 20Hz-20kHz (±0.5dB) Product Size: 123*50*139mm/4.84*1.97*5.47"(L*W*H) Headphone impedance matching is 16-300ΩT8 Can be perfectly compatible with iPod, Phone, MP3, TV, Echo Dot, laptop, desktop computer or other streaming media players etc., Satisfy most requirements of common home audio system use. Features QCC3031 Bluetooth 5.0, support Qualcomm aptX and aptX HD With Bluetooth/RCA/PC-USB/COA/OPT Audio inputs Vacuum tube: 6N3, can replace tube by GE5657,396A,2c51,12BA4,5670,6H3n PC-USB support operating system: XP/W10/MAC/linux RCA & 3.5mm headphone Audio output Selectable With DC 12V Power Adapter With OLED digital display FQA： Q: All my wires are connected. Why is there no sound? A: 1. Check whether the machine is turned on and whether it has switched to the corresponding input channel. 2. Check whether the back-end connection is correct and whether the volume is in the minimum state. 3. If all the above are normal, check whether the input playback device is silent, paused, or the volume is at its minimum. Q: Why can't I search for bluetooth pairing names? A: Due to the design of this machine, bluetooth does not work when using other channels for input. You just need to switch the input to Bluetooth mode. Q: Why does the sound break A: Although this product is the front stage of DAC, it also has the function of amplification. If the volume of the rear stage device is turned up to the maximum, the volume of the front stage is also turned up to the maximum, which is easy to distort. At this time, you just need to turn down the volume of the front stage or the rear stage. Q: Why is there a lot of electrical noise from the horn? A: If you are not using the original standard power supply, please replace the power supply and test again.Many power supply ripple interference factor is large will cause a lot of current sound. Q: Why does the speaker make a loud buzzing sound when I plug in the input cord and don't play the audio source? A: when the signal line without shield is used, the interference signal will enter the power amplifier for amplification. Replacing the signal line with shield can effectively solve the interference sound, or unplug the signal line.