So I finally got to audition this one in close details, and a few things jumped out to me. Please keep in mind my frame of reference is a modded HD600...
- There is certainly a lack of warmth with this headphone in comparison to the HD600. Something about the lower mids is lacking. Probably an FR thing? I certainly hear this thing much like most other closed headphones... which also seem to lack a bit of low mids. Maybe I'm spoiled by HD600?
- Upper midrange and lower treble is indeed a bit too elevated compared to my HD600. Nothing offensive, though, and I think I know the exact thing to do to even this out, as I have done with the HD600. At times, this emphasis causes a slight disconnect in the vocal range of some artists that I listen to regularly, so... it absolutely has to go.
- Low bass and mid bass are not as elevated as my reference. The PM-3 is actually a bit soft in this regard. Impact is not particularly strong with this headphone. And yes, I took off my glasses. The headphone didn't really change all that much. Upper bass and low mid are also lacking, as mentioned. Perhaps it's that the HD600 has a slight elevation down there that I hear? But ah well.
- Bass is indeed a bit thick, and blurry compared to my HD600. It's unable to represent the full gradations of volume changes in Little By Little (Caribou Remix), whereas the HD600 can effortlessly recreate those without mucking up the soundscape. The PM-3 does an okay job here, but impact and texture are lacking more so than I thought. Perhaps I need a new amp?
- Midrange is this headphone's strong suit. It sounds fairly even and nothing is spotlit. There are some hot spots in certain recordings that both my HD600 and ES10 kinda "hide". At times, I could swear this headphone is a bit... not smooth and refined. The HD600 is much smoother and more refined in this regard.
- Treble is actually causing me to hesitate to get this headphone. It's a bit scratchy, grainy, kinda muted and somewhat too shimmering at times. Probably 10KHz is elevated much more so than I'm used to, and either 3-4KHz is doing something weird that not only disconnects some vocals, but also causes bad hot spots to appear. Now, in its defense, it's not doing anything offensive, and all things considered, it's not sibilant, peaky, piercing, or annoying. It's just slightly too hot sometimes for my ears. The HD600 is much smoother and much more laid back in comparison.
- Soundstage is weird here. I swear this headphone has some good clarity in the midrange, but then... extensions and distortion control seem lacking at both of the ends (bass and treble), so sometimes things appear unexpectedly much closer than they should be, and much more in my face whereas there are also times the PM-3 convinces me I'm simply listening to the HD600 on a bad amp. There is much to be done here.
- Imaging is also an interesting aspect of this headphone. The extra treble emphasis causes a slight sharpening filter that kind of spotlights everything. However, fine details are still blurry, and separation is not particularly good. Probably has to do with bass or low mid distortion. Despite being smoother, less sharp, the HD600 has much better imaging than the PM-3, and can accurately represent some instruments to my ears. At least more so than the PM-3.
- Separation is also not a strong suit of this headphone. Things sound bunched up and kinda... shimmery. Guitars sometimes get lost in male vocals, and so on. Macro details are very spotlit, while micro details are kinda... smoothed over? Hard to explain, but I can definitely say that my HD600 is much more detailed than the PM-3, perhaps not so with macro details, but micro details are definitely more evident.
So... having said all that, I like this one! If I had to take a headphone with no mod, I probably would have grabbed this over the HD600, and pair it with a super warm amp to take care of the slightly hot treble. We'll see... but I'm highly considering purchasing a pair just so I can do... things to it.