The MCM-20.4 employs a unique configuration, offering 16 input channels arranged into 2 subgroups of 8, plus 4 more channels hard wired left and right in pairs. Each front channel features center detent Pan and Fader concentric controls plus balanced insert and mute switches. 

4 auxiliary sends are provided; being AUX 1 &2 mono sends, while 3 is Stereo. Sends can be done Pre or Post Fader. Master send levels are provided as well. 

The insert send points always have the signal present, so they can be alternatively used as direct outputs for recording without additional patch bays.Each group has its own stereo fader and balanced insert point and all 4 stereo subgroups are passively summed into the master bus. The gain is restored by means of a 1073 style class A , transformer coupled, mic preamplifier, featuring a total of 4 transformers (2 each channel).

The master section is also provided with its own balanced insert point.All connections on the back are made by DSUB 25 connectors following the Tascam protocol, with the exception of the master bus connections, which are by dedicated XLRs.

The smart summing topology employed in the MCM series of mixers allows for an impressive headroom and surprising low noise figure for a 20 channel, vintage topology mixer. Special care has been taken on improving crosstalk and self-noise figures from those on the vintage designs in order to accommodate the new MCM mixers into the digital era. The transformer based class A output stage is able to deliver a full +26dBu output.