Mastering engineers must undo sonic artifacts introduced by flawed mixing monitors.

Evidence

Perpetuating the trend, some of these old bad-sounding loudspeakers now have modern versions, finding justification in claims that they accentuate certain sonic features during the tracking and mixing processes. This is subjective audio at work. Does it matter? It does if these “distinctive” sounding monitors are used to evaluate the final product. Some mastering engineers have commented that they can recognize when aberrant loudspeakers have been used in the mixing process and compensate for them with equalization. So, it matters to somebody. — Toole, Floyd E, Sound reproduction- the acoustics and…, 351