Output power: 120W Working voltage: positive and negative double 25V-double 45V with 8-ove speaker Plus or minus dual 25V- dual 35V with 4-ove speakers Output impedance: 4 -8 (not less than 4) Frequency response: 18-22000HZ Harmonic distortion: Less than 0.03% : 105dB Before commissioning the board, the heat sink must be installed and insulated. The large tube and warm tube must be installed on the same heat sink and the input end is short to the ground. Use a multimeter to measure the between the two points indicated by the in the following figure in DC millivolt gear. The adjustment assembly is counterproductive (the static current of the final stage tube is 0 in principle, avoiding the crossover distortion can be, not the bigger the better, remember!) . Material: abs colour: As shown Package Contents: 1 amplifier board Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.