My viewing of the material I posted leads me a similar conclusion that you've found. Essentially, although there is no way I can actually experience what you do when we listen to the same song on the same headphones, there are enough objective commonalities that I can trust much of what you (or anyone) says.
One strange thing I've found is that certain headphones that are described as "warm", "energetic", or "playful/engaging" are truly a description of someone's unknowable qualia. I get by "warm" it generally means that there is less emphasis on treble or that the treble is articulate without being overly powerful/bright and that perhaps the bass is "slower" and therefore has more extension/impact as so often found on closed-ear headphones. Yet I've experienced headphones that make material that sounds harsh on one pair morph into something that is simply more pleasing on another, and I'd call that feeling "warmth".
And to throw a curveball, I've also simply felt different about the same music through the same speakers/headphones on different days. Stress, dehydration, poor nutrition, and bad news can all blunt one's affect enough that their consciousness is impacted.
Why do I bring it up? Ultimately I hope that in some small way that consideration of the subjective would aid a potential reviewer in eliminating any bias that would lead someone to buy a set of poor sounding cans based on their recommendation. In a nutshell, I hope watching the videos I posted are a safety guard against hype. I bought a pair of $7 Monoprice earbuds because there's currently a meme going around that these are "diamonds in the rough", superior sounding IEMs made possible by cheap Chinese labor/materials. I'm not impressed by them, I've returned them, and my guess is that this forum is prone to the proliferation of memes or groupthink about finding products who's price/performance is exceptional. This might be the case with the ATH-M50, so I'm reading each review from this perspective of potential placebo effect.
