The job of the mixer during the sound system load-in is discussed in this chapter. This job is essentially described as being the leader and “answer person,” who either has the answers to any questions that arise, or can find them as quickly as possible. A major part of the mixer’s load-in job involves the FOH (front-of-house) setup and this aspect of load-in is discussed in detail. The tools needed by a mixer during load-in are listed. The author suggests three small tools that he considers essential in a mixer’s toolkit: a Noise Plug, a SoundPlug, and a Tone Plug. He discusses the use of these during load-in and test. Keywords Cadac console, digital sound console, FOH, front of house, Noise Plug, noise tracing, sound mixer position, sound mixer duties, sound system load-in, SoundPlug, theatre load-in process, theatre sound take-in, Tone Plug