WIDELY USED Four input channels for you to blend various audio sources or instrument down into one channel. You can mixing guitar, electronic drum, MP3 player, phone music together then enjoy the reverb you’ve made. HIGH SOUND QUALITY No hum hissing and audible noise added into the system, pretty transparent, fluent sound streaming, 4 channels stereo mixer give the nice and pleasure experiences when you are using. STEREO CHANNEL The audio mixer 4 channel has four 1/4 TRS inputs along with an 1/4 TRS output, the channels are stereo not mono. FLEXIBILITY CONTROL Four volume knobs of stereo mixer led on the front panel to adjust each input level. Caution: 1. If the audio input is mono, or if you use mono cable for connecting the devices to EITHER the input or output of the mixer, the output will be mono. 2. You will need to use stereo cables (2 rings on the tip) to connect your devices to BOTH the input and output of the mixer, if you want to get stereo output. 3. Please add a ground loop noise isolator on the line from your device to the mixer, if there is humming buzzing noise.