mixer allen heath 4 channel, & HEATH Xone-42 Professional 4 channel DJ mixer with USB, Amazon.com: Allen & Heath ZED-420 – Touring Quality Audio Mixer with 16 Mono and 4 Stereo Inputs, 4 Groups, 6 Aux/Monitor Sends, 7x2 Matrix and USB I/O (AH-ZED-420) : Musical Instruments