Features With 3.5mm RCA inputs and outputs, can be compatible with many devices and satisfied many usage scenarios. Design NE5532 preamplifier compensation and a 0db/-15db switch that supports passive and active working: When the switch pops up, it can be used as an attenuated tone circuit in a passive state, with a gain of -15 dB. When the switch is pressed, it should be connected to the power adapter first and it will work in an active state with a gain of 0db(input and output signal are the same). With 3-adjustment knobs, support adjusts the main volume, treble and bass respectively according to your preference. Parameters Audio input: 3.5mm per Stereo RCA Audio output: 3.5mm per Stereo RCA Gain: 0db/ -15dB Power supply: DC 12-24V(5.5*2.1) Dimensions(W*D*H): 53*88*38mm*2.08*3.46*1.49in Net weight: 200g/0.44lb Package weight: 300g/0.66lb Packing list 1*Tone Controller 1*Power Adapter