Awesome thread!
I went to a Best Buy Magnolia today to buy some headphones for my commute and ending up buying a P7. Here are my brief impressions of the headphones I demoed at the store, playing 320 kbps mp3s through Neutron on my LG G2. YMMV.
AKG K550 -- I went into the store wanting to like these, but the glaring, congested upper midrange/ lower treble ruined it for me. Otherwise, they were decent. The bass was definitely above neutral, but it was extended, punchy, and kept the midbass in control. I did not find the soundstage to be particularly remarkable--it was on the large side for a closed headphone but the size is wasted because it sounds congested and flat. Isolation was meh. The build was better than I was expecting, especially the metal headband I never noticed in pictures, but they are still about half plastic. Very solid with little wiggle in the joints.
B&O H6 -- Didn't listen to these much as I could tell right away they weren't for me. The soundstage and imaging were very good, but the bass was just too "neutral" for me. Similar to or less than my old Q701, definitely less than my AD900X. The treble was smooth and they were polite-sounding overall. Build quality is excellent, similar to the P7s. All metal and leather. The H6 is very light, lighter than the P7.
Sennheiser Momentum Over Ear -- Holy moly these are dark headphones. Once my brain adjusted to the signature, though, the sound had a natural, relaxed signature that I enjoyed. I decided against them because I found myself turning the volume up too loud to bring out the treble. The bass was also a little too boomy for me. Also, even though they are built with nice materials, there is a flimsiness to them that is ultimately unsatisfying IMO. The earcups were too small for my ears as well. Barely circumaural.
B&W P7 -- The winner. They aren't neutral by any stretch, but I find their coloration enjoyable and they have enough clarity/ resolution that I won't be missing my Vibros too much on the train. The overall signature is V-shaped, but the V is skewed more towards the bass.
The bass is boosted to the point of sounding disembodied on some tracks, but it isn't bloated. Just thick, heavy and well-extended. The treble, on the other hand, is emphasized enough to give the headphones an icy sparkle on top of the bass. It's a little peaky and does get fatiguing after an hour or so. I'd put the treble in the same offensiveness ballpark as the DT-990 Pro. In spite of these drawbacks, though, the P7 just gets my toes tapping. I suppose that's the tradeoff with V-shaped headphones.
The soundstage is medium sized but the V-shape brings a nice sense of clarity and openness. Imaging is decently 3D but on the diffuse side. Detail retrieval, resolution, air, and ambience are all at a level that I find appropriate (though not exceptional) for a $400 headphone. The P7 was a clear step above the K550 and Momentum in these areas IMO. That's really what did it for me--these are headphones that I can use without feeling like I'm wasting my time by leaving my Vibros at home. The build quality is pretty sweet too.
(Dis)honorable mentions:
B&W P5 -- I hate supra aural headphones and only tried them because I was curious. Maybe I had fit issues because they sounded like total garbage. The soundstage was flat and small and the bass had terrible extension.
PSB M4U2 -- The batteries were out and sound only came from one side in passive mode. Obviously they were broken. Fairly or not, that gave me a bad impression considering all the other other headphones had stood up to demo use just fine. I also found them uncomfortable.
