Which button directs the output of any fader to the MTB?

The correct choice is the 24 button, as it specifically directs the output of any fader to the MTB (Mixing Tool Bus). This functionality is essential in audio mixing and editing, allowing the engineer to manage and route audio signals effectively throughout the mixing process.

The 24 button is typically designated for this purpose in mixing consoles, providing a clear and direct way to engage the routing of a fader's output to the MTB, enabling sound engineers to create balanced and controlled mixes. It is a vital part of setting up the overall signal flow within the audio mixing system.

Other choices, while relevant to a mixing console, serve different functions. The master button generally controls the overall output level of the mix, AUX sends are used for creating monitor mixes or sending audio to effects processors, and input flip typically refers to switching input routing configurations, not necessarily directing fader output to the MTB. Each of these functions plays a role in the mixing process, but the 24 button is specifically designed for the task of directing fader outputs to the MTB.