3.5mm headphone jack output is prior, which means stereo RCA and XLR output will auto disconnect when headphone is inserted. Parameters Chips: QCC5125 (Bluetooth chip) + CS4344 (DAC chip) Tubes: 2*JAN5725W Audio Input: Bluetooth / Balanced XLR / Stereo RCA Audio Output: Balanced XLR/Stereo RCA / 3.5mm headphone jack Bluetooth version: 5.0 (support LDAC 96khz/24Bit) RCA maximum output amplitude: 2V BAL maximum output amplitude: 4V Headphone output power: 120mW (32?) Headphone impedance range: 16-300? Distortion: 0.05% SNR: ?103dB Working voltage: DC 12V Input Sensitivity: 1Vrms Frequency response: 20Hz-20KHz (±1dB) Dimensions (W*D*H): 126*167*42mm / 4.96*6.57*1.65in Package dimensions (W*D*H): 310*240*70mm / 12.20*9.45*2.76in Net weight: 665g / 1.47lb Package weight: 1.0kg / 2.20lb Packing list 1*H8 Preamp 2*JAN5725W Tube 1*DC 12V Power Adapter 1*Bluetooth Antenna 1*Remote Control