Critical loudspeaker evaluation should use mono for fail-safe real-world listening

Evidence

Music and movie programs have intervals of monophonic, and nearly monophonic, sound. The talking heads on TV are a common example, and most of the dialog and much of the on-screen sound in movies is delivered by the center channel. All sounds hard-panned to a single loudspeaker are mono signals, even in contemporary “immersive” sound systems. It is therefore rational to perform the most critical loudspeaker evaluations in mono, as it is a fail-safe method from the perspective of sound quality while listening in the real world. — Toole, Floyd E, Sound reproduction- the acoustics and…, 464