Mackie HM Series, 4-Channel Headphone Amplifier Rackmount 4-ch x 12 Headphones (HM-400)
L/R main stereo inputs plus L/R stereo outputs
3 headphone outputs per channel
Aux input on each channel with balance control to mix main and aux signal
Mute and stereo/2-ch Mode switches per channel
12 total headphone outputs
