The 3124MV utilizes the same microphone preamp circuit that is used in all API consoles. It is equipped with the AP2516 input transformer and the proprietary output transformer found in all API mic pres and throughout the API product line. The unit offers Variable Output Level Control, switchable 3:1 output transformer selection, and an internal 48-volt phantom power supply, which is front panel switchable for each channel. Also provided is a front panel -20 dB pad switch that affects both the mic and line in. A 1/4" phone jack is available on the rear panel for each channel as an insert tip-send/ ring-return placed between the mic pre amp output and the mixer input.

Like the 3124V, the 3124MV provides up to 65 dB of gain. The Hi-Z front panel input goes directly to the op-amp, allowing a low level input such as a guitar or bass to be amplified without a matching transformer or direct box. This Hi-Z input can accept input levels as high as +20 dBu, making it perfect for keyboards and other high level devices. The rear output is an XLR connector.

Additionally, the 3124MV adds a stereo panner with a level control, and a post "fader" aux send. The stereo panners and the aux sends are bussed to master output controls and then to the rear panel jacks. A stereo AUX return is provided to return effects or cascade additional mixers for more inputs. The unique stereo aux return control acts to balance the left/right signal, yet staying stereo. It can also be used as a mono return.