Of course, your comments beg the question: how do you know a lot of music is poorly mastered? Could it be because you've been listening on an AD700? (Just kidding). Over the years I've believed certain CDs were poorly mastered only to get better equipment and find they're nowhere near as bad as I thought--in fact damn good, some of them. A mark of good equipment is that it makes the music sound better, not worse. When I try a phone, and I've just about tried them all, my initial criteria is: does it sound like music? Do I enjoy listening to music on it? I never think: Hmm, the bass lacks a bit of detail and doesn't quite reach to 40hz. One of the reasons the 650 is such a perennial favourite here is because it's musical--it actually sounds like music. Yes, it does roll off at the top, and that's a pity, and it does overall lack detail in the K701 sense, but it makes instruments sound like instruments, and in the face of that everything else is pretty much irrelevant.
As I said, I listen to classical/orchestral, so my crtieria may be different to those listening to rock, electronica etc, but this is after all a hi-fi forum, and the only criteria of hi-fi is: how well does it reproduce the original sound? I get a bit worried when I read sentences like, "I love my Denonbeyer HD43, it allows me to hear the guitarist's teeth clicking, but there's a bit of sibilance there and I can only listen for five minutes at a time. Should I get an Abrac 63 amp to tame that bit of brightness, or is it just a bad recording?" As someone who's been into headphones since 1970 I know instantly that the writer will not find happiness with that headphone and the Abrac 63 amp will not help, even if it costs $10,000. The real problem is that the writer has his priorities confused: he's listening for detail and excitement and the sound of the guitarist's teeth clicking when he should be asking himself: does this sound anything like what I heard at my last gig, or does it sound brighter and more exciting? I'm aware that with popular music the producer's aim is not always complete fidelity, that the music is sometimes fiddled with, but I still believe my basic criteria holds true: does it sound anything like live instruments? After all, if you start trying to second guess the CD producer where are you?
As for your point about different people preferring different presentations, is that true or just a consequence of people not being able to find the right presentation? After all, you wouldn't go to a concert of any kind and shout out that you didn't like the sound, that you'd prefer a different presentation please---"something a bit brighter, with more detail, to match my rig at home." Sorry to sound flippant, but that's what comes down to.
