Prof: We don't disagree here about, well, anything, I think. Granted: all causal relationships "presuppose" a connection between cause and effect, and the correlation (sorry: causation) between certain measurements and the correlative subjective impressions is probably no more problematic than most other supposed causal connections. Note, however, that I'm still being cagy here. Hume may be right: the difference between "correlation" and "causation" may be nothing more than "habitual expectation," common sense and physics notwithstanding. But I don't mean to drag philosophy into this again. I completely agree with you that there are "objective measurements" that reliably correlate with intersubjectively identifiable experiences; for audio professionals who work in the no-man's land between measurements (the science that created the equipment in the first place) and customers with desires and expectations, the objective language of measurements may be fully adequate to unambiguously identify features of an audio component that are sought in a given situation.
Sorry for the remarks about Descartes. I guessed you weren't confused about his "foundationalism." But I spent the last two weeks lecturing on Descartes; playing my role as "professor" is a hard habit to break.
Here's the main point, though, to return to the theme of this thread. Few of us are "audio professionals" who have witnessed again and again the correlation (or causation) between certain measurements and a given desired subjective effect. For us mere mortals, then, some kind of non-objective language is our only option in trying to express what turns us on in an audio system. What my OP was asking for was some sort of standard by means of which your subjective impressions can be communicated to me with sufficient clarity to persuade me that you are actually experiencing something I might also expect or want to experience from a given component. I can't have a pain in your tooth, but I can be persuaded by your language that you do. That's what I look for in posts that rave about some feature of our shared hobby.