Bryon wrote: "Admittedly, my operationalization is only a way to judge the RELATIVE level of coloration/neutrality of a system, not its ABSOLUTE level of coloration/neutrality."
Maybe it's possible to move the discussion in a slightly different direction with observations about reference points and relative vs. absolute measures. (On this tack I return to the notion of neutrality in the broad sense.)
Distinctions about coloration may be made relative to an external reference point of live music, or to an internal reference point of a previous or alternate iteration of one's system. Unfortunately fidelity to an external reference point will be debated ad nauseam, owing to endlessly varying opinions about live sound, as well as human frailty in reconstituting performance from memory.
So what internal references points are reliably available? Also, if one is to exclusively adopt internal reference points, any improvement is by definition relative to one’s current system rather than to an absolute. Bryon initially suggested two ideas to operationalize one’s aural judgment of neutrality—ideas about distinction and difference. I suggested that convergence was also a meaningful marker-- particularly the convergence of vinyl and digital sources through independent mod processes. Such convergence at least demonstrates CONSISTENCY between internal reference points. However the question arises as to whether such consistency merely reflects the bias of PREFERENCE rather than increased NEUTRALITY. Since all mods were made as single-variable changes on scientific grounds, I am inclined to view the progress as demonstrative of neutrality rather than personal preference. However others may reasonably disagree.
But more interestingly, can the scientific method be applied generally to the notion of subjective preference? Preference in this sense may be defined as movement toward one's PARTICULAR idea of live music. I believe the answer is yes to science, if the notion of personal preference is operationalized by the test that EVERY vectors of the listening experience must either be subjectively improved or remain unchanged. The basis here is to abandon the notion that colorations are a soup of isolated variables and combinations of inevitable compromises. If a system becomes more like that which one prefers in every sense (without a single shortcoming relative to prior iteration), then one may reliably conclude that neutrality is improved.
In practical terms, neutrality in this sense is the sum of positive vectors such as pitch, timbre, dynamics, frequency extension and control, spatiality, quiet background, and such others as one may consider important. The important thing is to develop an exhaustive list of significant variables and to listen carefully for each one. The test is made with respect to both the sum of variables and their differences. Even though these variables are not like terms, their differences can be measured with respect to the notion of preference, and positive must always be considered better. For the test of improved neutrality to be satisfied, no variable may go negative relative to another. A difficult test that few systems will pass—-but a test that forces the audiophile into a critical and uncompromising analysis of coloration.