[UNIFi]

Hmm.. Australian store has now got them up for $1699 AUD. Debating whether or not to bite the bullet and get them - pretty pricey but probably the exact sound signature I'm after for an open can.
 
EDIT: Doesn't seem like you can order yet? Neither does their linked resellers have it yet.

 

[tinyman392]

   
Well I don't think what happens after 10khz is the reason for these two cans sounding 'airy'.  The K701 rolled of aggressively right after 10khz...and no one can say they lacked air...but I do hear the K701 rolloff.  The HD650 actually sounds more treble extended but not as bright overall.  Also adjusting EQ sliders after 10khz also tends to boost or subdue 10khz to some degree due to the slope.
 
I hear nothing after 15khz...I thought I did...but looking at the spectrum analyser with a sineweep after 15khz tells me I do not hear what I see.

 
The Oppo rolls off more aggressive.  We can only measure raw measurements, and even then, we see variation in systems, especially in the treble.  However, Tyll's raw measurements of the 701 (all 3 that he measured, 2 K701 and 1 Q701) shows that the treble didn't drop below 5-15 dB from the 0 mark (measured at 1 kHz).  It also doesn't roll off as you get another peak at 20 kHz that is almost as high as the one at 10 khz.  I wouldn't say the K701 rolls off early based on that.  It drops a little, but doesn't "roll off" which could be why you get plenty of air.  The fact that the graph isn't declining at the 13-14 kHz range also helps this fact.  
 
The Oppo on the other hand do spike at 9 kHz, get another spike around 13-14, then drop dead (never "recover").  That second spike might provide some air though, so don't rule out airiness.  It could also be that the measurement setup that About.com is using rolls off the treble earlier than it should (and isn't compensated for).  In that case, all comparisons are nil and void as it doesn't seem they have any measurements of the 701 to my knowledge.  This is probably why it's a bad idea to read graphs for a source you're not familiar with.
 
On the other hand, my hearing personally starts rolling off around 14-15 kHz. 

 

[Headphoner]

  Alright, I bailed on the thread earlier.  It seems to be at least a little more polite, so I'll weigh back in.  Chris Marten's brief impressions were linked above, and I'll link them again HERE.
 
CAVEAT:  I was one of the Beta testers.  I had a great time participating in the test, I felt that I truly did participate - Oppo did give real credence to our input.  That said, we were a beta test group.  We listened, we criticized, we lauded, we bickered good-naturedly.  Oppo designed, redesigned, tweaked, brought in Igor Levitsky (I hope I didn't slaughter his last name) to do the real heavy lifting in tuning.  Many Oppo staff and Igor participated and were truly interested in our input.  It was a really cool experience.  I am predisposed to like these headphones for that reason - I helped just a little in creating them.  Oh, and Oppo gave each of the beta testers one of the first released retail package PM-1's.  This was completely unexpected and gracious.  Oppo really did right by the beta test, and the beta testers.  As I said, I am predisposed to view the PM-1's with rose colored glasses.  Take my comments below with a grain of salt.  Or not.  Those that have read my other gear comments know that I can be enthusiastic (fanboy) but I do try to be realistic, honest and at least reasonably objective in subjective comments.
 
Away we go!
 
Chris's impressions are pretty dead on save for the LCD3 comments. Reminiscent absolutely. I just find the PM-1 the easier, less fatiguing, more realistic and more pleasant listen. This from a guy who wasn't all that excited about the LCD2.2, but seriously considered parting with a kidney for the LCD3 (I had the pleasure of living with another head-fief's pair for about 3 or 4 days). 

The LCD3 transports me to a smokey 1930's speakeasy - men in silk suits, beautiful women, cigars, illicit booze, great jazz band and that stuff going on in the back room.  A stunning headphone. 

The PM-1 on the other hand, welcomes me home, takes my shoes off, sets me in a chair, invites a few friends over, hands us each a cigar and a sippin' whiskey or cognac and introduces the great band that materialized in the living room. Easy, but wonderful.  Yup, I like them a lot.
 
OK, that pretty much covers the emotional aspect of the PM-1's.  In fact, as far as I'm concerned, that may be all that really actually matters.
 
​For the gear heads out there (guilty) I'll do what I can here.
 
Yes - Extremely efficient.  They sound better out of an amp and a good source.  They sound really freakin' good out of an iPhone 5S though.  Really good.
 
They are feather weight for a planer, and pretty dang light anyway.
 
They are quite comfortable.  They may be the most comfortable planer I've worn - mostly because they are light.
 
​The bass is good, accurate, articulate and deep when needed.  It is not a bass tilted can though.
 
​The mids are lush and accurate.
 
The highs are detailed, again articulate, airy (barely) and smooth.
 
If you are looking for a boosted, euphonic bass or mid bass, the PM-1 might not be the right headphone.  If you are looking for a bright sparkle up top, the PM-1 might not be the right headphone.  If you are inclined to EQ for either trait - the PM-1 might be the right headphone (conjecture - haven't QE'd it).
 
​If you are looking for what I and others described, a pretty natural, lovely, easy headphone, you might be with me - the PM-1 is my new favorite open headphone.
 
Oh, build quality is excellent, the box and stuff is beautiful and helps with the whole cachet of "Statement Product."
 
OK, since this thread has teetered on the brink a few times, please, enjoy my comments, take them for what they are worth and leave it at that.  If you've heard them and vehemently disagree, blame it on different tastes, or the information in in my disclaimer.  If you haven't heard them….

Thanks for the informative review.  Have you tried EQ to restore the high treble and air?

 

[Headphoner]

   I am not concerned about the sharp roll off at the end of the band because it's beyond the human listening ability anyway

The roll off for the highs appears to begin around 9 kHz.  Many people can hear above 9 kHz.

 

[Headphoner]

  What Tyll's archive is missing is spectral decay; also it's difficult for me (moreso than from other reputable measurement sources) to interpret the treble behaviour with Tyll's FR plots.
 
As for what I mean by having measurements correlate strongly to my subjective perception; I have done lots of parametric equalization with sine waves in the past with M50s...kind of like how Bigshot does things. And with those experiences I ended up with a very specific perceived M50 frequency response for my own ears. Out of all the measurement sources on the internet, only 1 source has an M50 FR plot that corresponds perfectly to my independently-generated subjective M50 FR.
 
Correct compensation is mighty important.

Can you explain what you mean by compensation?

 

[Headphoner]

  Try using an EQ to cut frequencies after 10KHz. It loses a lot of air and sparkle. I would not like a headphone that has such a limited treble extension.

Using EQ to cut frequencies above 10 kHz not only loses a lot of air and sparkle but it also loses a lot of detail.  This holds for just about all instruments, including bass instruments.  If you are listening to a drum set and cut off the highs above 10 kHz, you will hear worse impact transients and less skin vibration detail.

 

[Headphoner]

It's a dimple at that frequency point lasting a good few kHz then picking up again hence allowing higher frequencies to get through however instruments like a piano for example does not even reach that point. Lots of instruments barely reach that point except for synthetic sounds like famous synthesizers. What most of us hear are harmonics and overtones at higher frequencies.

The harmonics and overtones are crucially important to high fidelity sound.

 

[Maxx134]

Using EQ to cut frequencies above 10 kHz not only loses a lot of air and sparkle but it also loses a lot of detail.  This holds for just about all instruments, including bass instruments. ...

This is why I DONT believe the previous graph(!) showing such a drop,
It is TOTAL BALONEY (!),
because what I heard had complete clarity, sounding superior to the AlphaDogs and on par at LCD detail level.
Edit:
Although I preferred LCD X the best.

(always wanted to post popcorn guy.)

me too..

 

[conquerator2]

^ that is exactly what we're trying to determine... Where exactly does it belong
Also, Alpha Dog is a closed headphone -_-

 

[vkalia]

  can you explain to me how slow decay in an headphone can result in good sound.. this is what we all want to know... if a sound wave stop in a recording and the headphone is still resonating... (is it possible that this could be good to add some kind of added decay texture to the sound... or it really can't be good since it's really adding something that wasnt in the recording.. since if a string resonate in the recording shouldnt it stop at the same moment in the ear..)

 
I'll take a stab.  I am not an audio engineer (although i am an engineer by training), and these is just my hypothesis, trying to correlate subjective preferences with objective science:
 
When you listen to, say, a violin in a concert, you hear the direct sound of the violin as well as reflected sound coming off the room.
 
When you listen to a violin on speakers, you heard the direct sound of the speakers as well as the reflected sound coming off the room (although the acoustics of a typical home listening room are going to be different from that of a concert hall).
 
When you listen to a violin on headphones, there are no reflections.
 
Unless your ear is tuned to the sound of a violin being played outdoors in an immensely-large field, you might find a sound with some added decay to be closer to what you are used to hearing in a concert.   Of course it is not exactly the same thing - but as listening science shows, the brain is very good at filling in some of the missing gaps.   Which is a certain degree of coloration can indeed be perceived as more life-like.

 

[Headphoner]

This is why I DONT believe the previous graph(!) showing such a drop,
It is TOTAL BALONEY (!),
because what I heard had complete clarity, sounding superior to the AlphaDogs and on par at LCD detail level.
 

I sure hope you are correct!

 

[murrays]

   
I'll take a stab.  I am not an audio engineer (although i am an engineer by training), and these is just my hypothesis, trying to correlate subjective preferences with objective science:
 
When you listen to, say, a violin in a concert, you hear the direct sound of the violin as well as reflected sound coming off the room.
 
When you listen to a violin on speakers, you heard the direct sound of the speakers as well as the reflected sound coming off the room (although the acoustics of a typical home listening room are going to be different from that of a concert hall).
 
When you listen to a violin on headphones, there are no reflections.
 
Unless your ear is tuned to the sound of a violin being played outdoors in an immensely-large field, you might find a sound with some added decay to be closer to what you are used to hearing in a concert.   Of course it is not exactly the same thing - but as listening science shows, the brain is very good at filling in some of the missing gaps.   Which is a certain degree of coloration can indeed be perceived as more life-like.

 
Consider, though, that the recording of the violin playing will also include in the recording the associated echo and reverberation from the original performance (as long as not recorded in an anechoic chamber).  Listening on headphones reproduces that original acoustic environment.  I hear plenty of reflections on headphones.

 

[vkalia]

  Consider, though, that the recording of the violin playing will also include in the recording the associated echo and reverberation from the original performance (as long as not recorded in an anechoic chamber).  Listening on headphones reproduces that original acoustic environment.  I hear plenty of reflections on headphones.

 
True that.   However, most orchestras are miked from a location that is different from that of the typical listener (usually, a lot closer).    And the ratio of direct/reflected sound, while present, is in a different proportion to what one hears in the hall.      If your reference is the sound of smaller, more intimate ensembles, then your reference would be different, and the gap between the recording and the reality would be lower as well.
 
It is interesting that the term "natural" has been applied to the Oppo, b/c all of us have a different reference for what is a natural sound.   If someone wants to reproduce the sound from a Metallica concert. then s/he will have a different definition of "natural" compared to someone who wants to reproduce the sound of a small jazz bar vs someone who wants to reproduce the sound of an full orchestra vs someone who wants to reproduce what is on the recording with perfect fidelity (without no direct references to actual performances).
 
That is why, as has been pointed out, even interpreting the response curves of speakers involves a fair degree of subjective evaluation.

 

[up late]

more first hand impressions less sound science guff please

 

[MattTCG]

^^ +1