Amazon.com: Line Mixer 4 Channel, Donner Low-Noise Mini Audio Mixer DC 12V with AC adapter & Stereo/Mono Adjustment, As Microphones, Guitars, Keyboards or Stage Sub Mixer, Ideal for Small Clubs or Bars :
Palm Size 4 Channel Micro Mixer
Henry Engineering MICROMIXER 4-input, 2-output Stereo Mixer - SCMS, Inc
Micro Mixer Sky PM-40 for Sale in Cutler Bay, FL - OfferUp