The Shure MX400SMP is a specialized surface-mount preamplifier unit designed to power and process signals from compatible gooseneck boundary microphones within the Microflex wired microphone ecosystem. It is engineered for permanent installation in conferencing tables, lecterns, and council chambers where a discreet, low-profile solution is required. The preamp provides the necessary phantom power to the connected condenser gooseneck microphone and includes essential audio processing, such as gain adjustment and possibly a low-cut filter, to optimize the microphone's signal before it is sent to a mixing console or DSP.

The unit is designed for flush mounting into a standard single-gang electrical wall box or a custom-cut opening in a table surface, presenting only a small, professional faceplate to the user. This installation method keeps the electronics accessible yet hidden, contributing to a clean and uncluttered aesthetic in boardrooms and meeting spaces. The preamp typically features intuitive controls, such as a rotary gain knob and status LED, accessible on its faceplate. Its output is a standard balanced XLR connection, which is routed through the wall or table structure to the central audio system.

The MX400SMP simplifies system design by decentralizing the microphone preamplification stage, allowing for shorter microphone cable runs and localized gain adjustment. It is a key component in creating high-quality, reliable installed audio systems for teleconferencing, voice reinforcement, and recording, where consistent performance and neat installation are critical.