The Rolls DB227 Podcast-Pro Microphone/Source mixer device was designed to mix a microphone with a source signal either RCA or 3.5mm (1/8") signals to a single XLR output at microphone level. The DB227 consists of two balanced XLR jacks, one female input, one male output. RCA input jacks and 3.5mm input jack. A level knob for the attenuation of the source inputs of the unit (RCA and 3.5mm only). It has switches for allowing the input signals to pass through to the output of the unit and a ground lift switch for grounding the input and outputs sections together to help eliminate ground hum issues.