A master word clock source would be connected to which component of the System 6000?

A master word clock source connects to the mainframe of the System 6000 because the mainframe serves as the central processing unit for the system and is responsible for managing audio signals and their synchronization. The word clock is essential for maintaining timing accuracy across multiple devices in a digital audio setup, ensuring they all operate seamlessly without drift.

The mainframe requires a stable word clock input to synchronize its internal processing with other digital audio equipment, allowing for precise timing essential in professional audio environments. Other components, like the remote CPU, TC Icon, and the power supply, do not serve this function; they each have different roles within the system—such as providing user interface controls or supplying power—rather than handling word clock synchronization. Thus, connecting a master word clock source ensures that the mainframe can achieve reliable timing for processing and playback of audio, making it the correct choice.