Fully functional. Often used in the studio and with some superficial marks from moving it from one rack to another. All inputs and the headphone outputs are standard jack sockets. Each of the four channels has seperate left and right mute buttons and can be switched to mono. Each of the four channels has an AUX input which can be mixed via a control knob with the main stereo input pro channel. The main input and each of the four headphone channels has its own volume knob.