Headfi user, hans030390's review of the Oppo PM-3 is the best review I've seen of the headphone. Neither my review, nor John Darko's review-and-factory-tour, is even close. Reviews of this calibre hitting headfi in the last few days are true triumphs of our community.

Hans030390's review is as richly illustrated with subjective listening impressions as it is with objective measurements. Bravo.

“In fact, the PM-3 actually has some improvements over the PM-1 and 2 to my ears regardless of having a more “fun” sound or not. For one, it seems to have more clarity across the frequency spectrum than its predecessors do. Transients seem faster and cleaner. Low-level details aren’t quite as masked. The PM-1 and 2 just have an inherently slower sound in comparison. No doubt, the PM-3’s frequency response plays into this perception, but I think it has some genuine improvements outside of that. For one, distortion seems better on the PM-3, but I’ll get into this in a bit. The PM-3 just seems to sound a bit cleaner and clearer in most ways than the PM-1 or 2. Snappier, if you will. Simple as that.

All in all, I think OPPO came close to nailing what they were aiming for. The PM-3 is not inherently meant to be the most neutral headphone ever, and that’s fine. It has a really engaging sound and seems to make some technical strides over the PM-1 and 2. Ideally, I think the treble response could be evened out a bit more so it’s not quite as bright sounding, and the mids could sound a bit thicker and better integrated, but I’m really nitpicking and don’t have much room to complain when you’re already getting so much at $400.”

Especially interesting to me is the fact that Hans uses an in-ear microphone rather than a dummy head or other simulative measurement device.

Read the entire review, it's worth it: OPPO PM-3 - Great Closed, On-The-Go Planar