The Listen 4 quarter of 4ms is a four-channel audio mixer that works perfectly as a backend mixer in a larger system. Inputs 1 and 2 are mono and have their own panorama controls, inputs 3 and 4 each have two sockets for true stereo. The only common inputs are the level control and the LED for monitoring the level of each channel. The main output with 6.3mm jacks can be switched between Stereo TRS and Balanced, additionally there is a separate volume control for the sum. Parallel to the master output there is a separately adjustable headphone output. At the back there are skirting boards for daisy chain operation, in order to be able to operate several Listen4 and/or Listen4 Quarters in a group.