Pre-Fade-Listen. Circuitry and buss in a mixer which takes the signal form a channel before the fader and routes it to an isolated monitor system (usually headphones). This feature allows the operator to hear what a channel sounds like BEFORE it's turned on. This is helpful for checking up on wireless microphones (to see if they've been turned on) and to help identify who’s using what microphone. More than one channel can be PFL'd at once. Also known as a cue switch or solo switch.