RDL ST-UMX3 Audio Mixer 3 Mic or Line x 1 Mic or Line, Balanced Unbalanced Configuration Audio Mixing with Up To Three Inputs. Switch-Selectable Mic or Line Inputs. Switch-Selectable Mic or Line Output. Add Additional Microphone or Line Level Inputs to an Existing Mixer. Combine Signals of Different Level, Impedance or Balanced Unbalanced Configuration.