1. When the scale line on the treble and bass knob points to the direction of 12 o 'clock, it means the gain is 0dB.
2. 3.5mm headphone jack output is prior, banana speakers and 3.5mm AUX outputs will be auto disconnecedt when headphone is connected. 
3. Pluggable tube socket, default 6*4N vacuum tubes, can be replaced by 6J1 / 6J2 /6J3 / 6J4 / 6J5 / 6K4 / 6*1N / 5654 / 6AK5 /EF95 / JAN5725 /6*5N /403B etc.


Specification
Audio input: Bluetooth 5.1 / stereo L/R RCA
Audio output: banana speaker jacks / 3.5mm headphone jack / 3.5mm AUX
Bluetooth chip: QCC5125 (support APTX/APTX-LL/APTX-HD/LDAC)
Amp IC: Infineon 12070
Sampling rate Bluetooth supported: 24Bit/96KHz
Max output power: 80W+80W(4Ω)
Matched speaker impedance: 4-8Ω
Maximum output power of earphone: 130mW×2 (32Ω)
Matched headphone impedance: 16-300Ω
Treble / bass adjustment range: ±6dB
Frequency Range: 20Hz-20kHz (±3dB)
Input sensitivity: 0.775V
SNR: ≥ 96dB
THD: 0.1%
Decroative LED color: green / orange / turn off
Working voltage: DC 15-24V
Dimensions(W*D*H): 132*142*35mm 
Package Dimensions(W*D*H): 310*240*70mm  
Net weight: 566g 
Package weight: 1.2kg 

Packing List
1* Amplifier
2* 6*4N Tube
1* 24V Power Supply
1* Bluetooth Antenna
1* Acrylic Board
1* User Manual