SMSL Audio Sap-II PRO Black Headphone Amplifier, Black 2 way switch input circuit 35 earphone seat and the RCA block Replacement of the input signal is no longer need to pull line just select the switch panel high precision power divider high input and output connection seat to ensure the signal channel is smooth and durable audio channel all use the United States Army Regulation DALE have a fever resistance Low noise sound quality is good Technical specifications: The standard input interface: 3.5mm/RCA stereo input (with switching) Output interface: 6.35mm earphone seat