The Coleman Audio TC4 is a DAW monitor controller for mastering, or any studio. There are two balanced stereo inputs, a completely passive signal path through a 47-position stepped attenuator, that tracks to .05dB, and maintains the stereo balance at any level. This feeds the mains or alternate balanced speaker outputs. There are four balanced stereo inserts in the signal chain with relay switching to keep the signal path as passive as possible. This makes A/Bing compressors, limiters, EQ or any effect as easy as pushing the button to insert the piece of gear. The flip switch reverses the order of insert 1 and 2 so you can A/B which comes first, the compressor or EQ. The mono switch sums the stereo signal to mono in the speakers only not the mix output. The phase reverse switch flips the phase on the right speaker output, and when used in conjunction with the mono switch will give you a left minus right so you can work on the signal channels (hard L or R signals). There are L and R mute switches to isolate the speakers and help focus on the side channels. The PRE/POST switch allows a comparison between the original audio signal and the processed audio signal. The Master Output signal has a completely passive signal path from start to finish, except of course for the insert devices, and makes it easy to print the final mix. A powerful engineers headphone output with its own level control, to check mixes up close, and a balanced stereo meter output so you can watch your levels rounds out this 1U monitor controller.