Headphoneus Supremus
Pros: Stylish Sound
Cons: No longer in production.
After spending some time with my new Oppo PM-2s today, and yes i know im late to the party as these have been around for a while and are no longer in production...... Yet, ive wanted to own them and just have not pulled the purchase trigger until recently...
(nothing tried, nothing gained)
(don't wait for life to find you, instead, take your talent and your dreams and your time and build the life you want.).
So, after spending some time with them, i thought to post a few photos, and write a few comments regarding what they offer the ears and also the pleasure center within my brain.
And on both accounts, they offer quite a bit.

On the ears, they are 8.5 in comfort, feel pleasant and have no unreasonable pressure issues/points with the band or the cups.
They are not light as a feather, but this is owning to their stylish tho industrial design & materials.
Ear cups are medium-sized and will never be too large.
Which all together means, wearing them is not a hardship and admiring their build quality is a certainty.
If Apple made a designer set of headphones that mattered, then these would be the evolution of that blueprint.
They are sleek and expertly crafted, with a hint of aesthetic elegance.
And that is exactly how they sound..... They sound exactly like they look......sleek, expertly crafted, with a hint of aesthetic sonic elegance.

When i first connected them to signal and my ears became their focus i felt they were very tonally smooth, and a tad polite.
But as my brain/ears began to sync with their sound, i realized that their smooth was their resolution and their polite was the way they manifest a lot of micro detail without sounding at all harsh within their upper treble frequency.
There is no 6-8kHz glare to be found.
Also, and something unusual for a set of headphones, is that the PM-2s have the ability to let your ears see all the detail in the music, yet, not because of anything related to treble frequency "crutch".

(TFC) is : when a badly designed headphone sound that is lacking resolution is overcompensated by..... jacking up/overcooking/hyper-extending.....the treble response.
Well, no such sin is being committed inside these high tech'd aluminum framed beauties......as they have all the resolution you want, and have a somewhat smooth tonality as well.
Now, if you are into something like the recent HiFiman Ananda or similar, and are looking for that extra not truly natural insight detail that some headphones can give you at the expense of musical beauty, then the PM-2s will get you about 94% of this type of hyper-realism, yet, not so much of it that the music falsely glitters and shines at the expense of naturalness regarding overall tonality.


Soundstage / Soundstage depth : Better then average, with very nice instrument separation.

Bass : Somewhat extended, slightly round yet authentic. Kick drums kick and bass guitar pumps, but this is a bass response that respects the midrange and sounds very balanced.

Midrange : fluid, polished, elegant.

Treble : Not rolled off & not overextended. Cymbals are clean without sizzle, and acoustic guitars sparkle without sounding thin. Once again, very balanced, nicely detailed without anything harsh or edgy.
Tyll felt the treble was a bit "artificial", but i perceive it to be very controlled/balanced and not compensated by 6-8kHz over-extension.
I can't think of any other headphones that sound like the PM-2s.
They have their own thing going on., and i like it.
Maybe you will also if you reach for a pair with your bank account, someday.

Overall Tonality : Controlled, polished, refined, expertly designed.

Who will love them? : Discerning Listeners who can afford to love and appreciate more then just a few sets of very good sounding headphones, and enjoy a well made attractive product.

Who will hate them ? : Buyers who are looking for only "one great headphone" and the "where is the extra treble, these don't sound like Beyers or AudioTech's", crowd.










Excellent review!


1000+ Head-Fier
Pros: Excellent build quality, wonderfully comfortable, truly exquisite sound.
Cons: Upper treble rolls off
Firstly, I have to give a major shout out and thanks to @Jiffy Squid for accepting me into the reviewers program for @Oppo. I’ve had the honor of listening to all three planar magnetic models offered by Oppo and firmly believe their competence in audio is truly something to behold.
    As an avid fan of the PM-1 I had to try the PM-2 because from what I gathered, the only difference other than being $400 cheaper, is you don’t get the mega extravagant box and complete set of pads. Sonically the PM-1 and PM-2 are the same sharing the exact same driver,  but let’s dive in to this and find out for ourselves shall we? Also as mentioned above, this is a loaner/review unit so your experience may vary some.
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The Opening Experience
    I can’t give a full unboxing experience of the PM-2’s being that these were a review unit but like the PM-1’s these came with 2 sets of leather pads (small and large) and my oh so favorite and loved velour pads (if you can equip your cans with velour pads, do it, thank me later). A quick note however is these DO NOT come with all 3 pads, only the review unit did. You will have to purchase your desired pad (if not already equipped) separately.
    Also received is the outstandingly well made 10 foot cable that is not just well made but awesome looking as well. As for the portable cable, it’s still the very cheap looking and feeling one.
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    Just like their bigger brothers, these are stunningly made. Rather you’re more interested in aesthetics or a super durable build these are absolutely world class and do not disappoint me in any sense of the word (except for the mobile cable).
    The frame is made of very nice *lamb skin I believe* leather and just feels sturdy in my hand. The framework that holds the drive units are also very well put together but unlike the PM-1’s shiny and well polished aluminum, these are made of a matted very hard plastic instead.
    The cushions are easily detachable which allows one to easily replace and equip the desired pads of their choosing.
The 10ft. amp. cable is wonderfully well done and well shielded from outside interference, the jacks feel sturdy on both ends and I feel no worries about having them for years on end.
    The mobile cable however is like Harry Potter. This thing was given absolutely no love and feels as if it was thrown together with whatever was laying around like Harry was thrown under the stair case. It kinks up all the time and *at least the review unit I receiver* the jacks that connect to the headphone protective plastic comes off if I don’t death pinch them. So please do yourself a favor and buy a competent 3rd party cable mobile for these or get the @MoonAudio Silver Dragon cable if you really want to extract every single note of detail. Quick note: yes these are a review unit that’s been heavily used but I expect this to happen to anyones mobile cable.
    Have you ever wondered what a cloud would be like if it gave you a firm hug? Put on a pair on PM-2/1’s and you’ll know. The headband sits perfectly still on my head and doesn’t irritate my hair whatsoever (and I keep it ⅛” buzz cut). It has the right amount of give and support that never once during my longest (i.e. 5+ hours) sessions was I ever uncomfortable or required adjustment. The earpads, especially the velour ones, have the perfect amount of clamping force and are the best example of the goldilocks effect. What more is despite the bulk of these, they don’t hardly weigh anything, so that’s yet another box you can mark off the checklist.
    Just like the PM-1’s, after listening to these I’m left awe struck and satisfied. The PM-2’s are oh so full sounding and, to me, leave nothing to be desired. These also carry a potential downside (depending on how you look at it), and that’s they don’t scale well. These sound relatively the same regardless if I’m playing from my phone or my Project Horizon 3 tube amp., henceforth I don’t feel the need to individualize the sound before and after external amplification.
    I found the PM-2’s to overall be very neutral but with a warm inviting hint of warmth. They were wonderfully transparent and provided great imaging to whatever I was listening to from “The Pride” from Five Finger Death Punch to “For All Seasons” by Yanni. I truly felt at the performance.
    Like the PM-1 the only downside I could find with these only exist if you consider them a full open back design over a semi-open, and it’s that they’re not as open or airy sounding as open backs are traditionally known for.
    Excellently clean and accurate. The treble extends very high and the energy transfer from the notes to your emotions are terrific and will definitely give you chills.
    The only downside with these which sonically that I’ve found and it’s not even that large is that at the upper treble range, it tends to roll off instead of extending further.
    Just like with the PM-1’s, I’m in heaven with these. The mids are strikingly neutral and very precise. I honestly have zero complaints with the mids, they’re perfect.
    Out freaking standing is what comes to mind when thinking about the bass response. As I’ve grown to expect from planar magnetic headphones, the bass is incredibly tight and controlled. The warmth presented is exactly what I like in audio and can produce the bass hit when the music demands without layering over the other tones.
    To sum up the younger brother of the masterpiece that is the PM-1’s, these are truly a defining headphone and a new standard for what I prefer in audio. The quality, craftsmanship and presentation are above and beyond almost anything regardless of price range. The PM-2’s can also play well with lower tier audio files but I’d definitely recommend no less that FLAC if applicable.
Finally, for those of you who are like myself and have fallen in love with the PM-1’s but the intimidating $1,100 price point deters you then you can absolutely make yourself at home with the PM-2’s. At $700, sonically there are the exact same and aesthetically you’re only missing out on a shiny finish, the extra pads and the very extravagant box. So like flagship bigger brothers, if you’re looking for a wonderful, sub elite class tier headphone that performs exactly like an elite class,  that’s extremely well built, very accurate and neutral, and benchmark setting comfort, or in other words a very close to perfect headphone. Then the Oppo Planar Magnetic (PM) 2’s are definitely for you.
Till next time my friends, also make sure you check out my unboxing video here, and my full video review here!
No problem friend but these are the PM-2. My PM-1 review can be found here. But absolutely! These played with almost the same clarity as when I played them through my Garage1217 Project Horizon 3 tube amp. So playing from your DAP won't have any issues driving these, in fact it might even be better for the DACs in DAPs are usually pretty good. So fret not my friend you're great to go. And freely ask me any question you have I'll try my best to answer them.
Makiah S
Makiah S
I kinda liked these when I had them, I honestly found them to be dull... yes they are really cohesive,  LIKE REALLY, simmilar to the HE X in that the sounded really good with many of my sources, an that strength was also imo a weakness... 
still though... it's one of the most balanced headphones I've ever heard! Just not aggressive enough or tactile enough for my tastes 
Excellent review!


Headphoneus Supremus
Before we start, I have to admit to a bias; the description of a Libra fits me pretty well. I love balance and an even-handed approach to everything. A little bit more about the libra personality: we are diplomatic, hospitable, peace-loving, and idealistic. We're also sometimes vain! Acoustically, I love many different kinds of sounds, I also play a lot of videogames, and I tend to have long listening marathons. Fortunately, the Oppo PM-2 is the Libra headphone!


Sound Signature
Balance. That's what the PM-2 is all about. I don't detect major spotlights on particular frequencies, mainly the headphone speaks honest-to-the-recording. This makes the PM-2 a sociable creature that can easily hang with the R&B crowd, speed along quickly with some metal, or recline dreamily with the parlor piano. This chameleon quality makes the PM-2 score pretty high on transparency, but without obvious colorations it doesn't obviously put on rose-tinted glasses to satisfy bass heads or treble heads. If I listen through a whole song or two, the Oppo's strengths in note separation, imaging, quick leading impact, and low distortion and note bloom really can draw in the listener.

Generally mids do have a bit of meat on them and are engaging, but still balanced and not "thick" like the mids on a Sennheiser HD700. Treble is slightly less hot than I'm used to from my AKGs, but in a nice "red wine audiophile" way; I don't find it veiled, and in fact I really appreciate the fatigue-free experience for 3+ hours of listening. Playing my favorite CoD4:MW, I used to hate it when someone called in a helicopter; of all the guns in that game, the staccato slicing sound of the chopper gun is the most irritating. My old Audio Technica ATH-AD700 could get irritating, the AKG Q701 was better but would still make me wince sometimes, the Beyerdynamic DT880 would leave my ears ringing, but the only irritation I feel with the Oppo is if the chopper kills me... I could hear it coming, I knew better! Bass is always low distortion and articulate, extending deeper than the PM-3 with "Undisclosed Desires of the Heart" by Muse and making a fairly strong showing in "Angel" by Massive Attack, but never bleeding over my ability to hear over other instruments and only thumping on the door when called on.

Listening to a FLAC of Hans Zimmer's "What Are You Going to Do When You Aren't Saving the World?" from that Superman movie displays an ease of creating notes, nice sense of soundstage depth at the beginning. Piano notes have nice impact and "meat" and weight, bass can be both light and airy or pound with strong impact, cellos at the beginning are nice with well-rosin'd bows, subtle "breath of air" sound effect @ 1:20, piano twinkles don't get lost in congestion when the horn crescendo starts and in general the PM-2 does well in not burying any instrument during complex passages.

Cowboy Junkies' super slow and intimate "Walking After Midnight" has even more intimate vocal closeness than the AKG K612, but a nice sense of sounds echoing off deep into the room, smooth guitar picking, harmonica has nice surprise impact but just on the right side of sharp without going too far to "Ouch!"

"Undisclosed Desires" – Bass notes balanced-strong, not underwhelming like PM-3, can hear the (intentional) digital combing effect to synth sustain and voice (like when you hum into fan blades). Good impact throughout freq range. Sub-subterranean bass in the last 19 seconds is Felt!

"Cracks (Flux Pavillion Remix)"
Yes, it has the wub wubs. Emotional, moves you up and down with the tones (always found this track easy to dance to). Xylophone has magic. The spine chills, they happen!

"I can fly" by Miss / Mister – Nice female vocals, really get a sense of when she uses her lip on her teeth or a little moisture to her lips.


The PM-2 is the good child which plays well with home or portable systems. One way Oppo achieved this was with a double-sided diaphragm that's quite efficient, with relatively low impedance (32 Ohms) and high sensitivity (102 dB in 1mW). The other system "hospitable" aspect of the PM-2 is Planar Magnetic's purely resistive impedance, meaning that you can ignore the 1/8 output impedance amping guideline. If you don't know what that is, stay innocent – a whole can of worms is not an easy thing to swallow! With my iPhone 5s, I heard a surprisingly capable and full experience; plugging it into my home reference system (with a Theta Pro Basic II DAC) yielded a little better dynamic "impact," slightly more meat on the bass and mids, and extended soundstage depth, but the iPhone still had great resolution and extension without sounding harsh. I give any and all sonic improvements to the multibit DAC because the PM-2 doesn't need a special amp to "fix" flubby bass or grainy distortion. Oppo bucks the trends set by Audeze and HiFiman where Planar Magnetic drivers earned a reputation as some of the most power-hungry tech on the market among headphones.

It's also light weight for a Planar. Sure, the 385g PM-2 is heavier than my all-plastic headphones, but considering all the leather, metal, and plastic that goes into the build, the weight is an achievement and noticeably nicer than (again) the other Planar Magnetic headphones on the market. The weight and its distribution (Oppo even published the clamping force in the spec sheet: 5 newtons!) make for a headphone I can wear long-term during an Iron Banner event in Destiny. My casual-earclip-toting fiancée notices the weight, but ON HER OWN listened to three songs instead of just the usual 42 seconds and "That's nice dear."

The earpads and cables are easily swappable and Oppo (separately) offers pads of different materials and balanced cables (2.5mm jack in the headphone). Replaceable cables give peace-of-mind for a headphone of this price, and it's cool to customize cabling for my amp. I usually loathe leathery earpads, but these latex ones wrapped in pleather don't trap heat as much as some others, resist moisture absorption (I was like 15th in line for the loaner program, and the pads didn't feel grease city at all!), and were still nice and springy.

Apparently, these PM-2 "alt" pads helped bring out some treble which people complained was missing from the PM-1's default pad. My own cursory swap didn't immediately detect a huge drop in treble, but it probably would've taken more songs to really notice. I spent half of my time with the velour-wrapped earpads, which I found gloriously comfortable despite the front to back width being narrow enough that the back of my ears would often be slightly covered by the pads. The pads swap super easily, with plastic pegs reminiscent of reattaching speaker cover screens.

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Cool Factor
The PM-2 won't get you a hot date or show off in a big way to your friends, but it is a headphone you could show your spouse (without getting slapped in the face), could be your best buddy at the office, or could help you let go of tension at the end of the day.

It has the functional "first kind of cool" of being a very capable headphone, in spades, but not cool in being specialized for "The phatest bass you've ever heard!" or "Massive amphitheater Soundstage". A Coworker, let's call him "tin-ears" to protect his dignity/anonymity, wore them for 2 minutes and remarked that they didn't sound "much different" from his EarPods (compared to going to his Beats Studios), but almost immediately after putting his earpods back on came back and suddenly rattled off a bunch of ways his earpods weren't as good.

Form and size-wise, it's maybe a bit bigger than would look great while walking down the street, but this full-sized headphone embraces a unique rounded-rectangular aesthetic that really sets it apart from most headphones. However, this is still the Libra headphone... the PM-2 isn't unique like the purple Audio Technica ATH-AD700 with head "wings." Oppo decided to balance the uniqueness by using traditional headband/yolk shapes, traditionally classy but low-key materials like black leather and brushed metal, and understated style accents. The Selvedge premium denim case is something new, encouraging me to fold the earcups flat and have it accompany me to work. So it's unique, but in a handsome and upscale way rather than unique in a wild way.

Not as collectible "Cool" as the PM-1 with all that model's included accessories, display case, and premium price, but the PM-2 saves a "cool" $400.

Best Use Scenario
The PM-2 is a gentlemanly headphone, transporting neatly to accompany you to the office or library. It's Forward and Musical, rather than brightly analytical, so this is probably not the choice headphone for mastering engineers. Suitable for long-relationships and a genre chameleon, I wore these for hours while gaming first person games with surround, but it's equally suited for hi-fi music listening marathons on "shuffle" mode. Finally, the Oppo might make your expensive, fancy amp seem redundant, make theaters seem overpriced, and make you contemplate raw denim jeans, but in the long run the PM-2 is a satisfying value that excels at showing off great audio files and a quality DAC.

Attractive, hospitable to playing off of most devices, skillful at diplomatically playing almost anything, almost ideal for extended listening... Now that's a Libra Headphone!
Great review. I've actually come back to it a few times now to revisit my own impressions, the compare. (Great to meet you and your Fiancé @Larkburger too!)
Excellent review!


100+ Head-Fier
Pros: Best Design & Build, Comfort (for me), Bass, Lush Mids, Easy to Drive
Cons: Recessed Treble, Poor Scaling with Good Amps
I’m sure you’ve heard a lot about the PM-2. They are Oppo’s second attempt at making waves in the upper-tier headphone market, but seemingly to no avail. I’ve personally never seen these headphones being praised on the forum and at first listen, I could see why. After further listening, I realized that most Head-Fi’ers have been looking at these headphones all wrong and I’ll tell you why. I encourage you to read my full review with an open mind, but if nothing else, the answer to my teaser can be found in the conclusion.
I am in no way affiliated with Oppo. Nor am I am being compensated in any way for my review. I received the PM-2 through the loaner program for trial purposes. Special thanks to Jiffy Squid and all of Oppo for providing me the opportunity to demo these headphones.
The opinions offered in the following review are my own. As always, your ears may differ from mine.
All pictures in this review were taken by myself and are owned by me. Please contact me if you wish to use them.
Testing Rigs
All testing was done with CD Quality, 16/44.1khz FLAC files
Oneplus One
HA-Info U2 Plus USB DAC/Amp (Basically half O2+ODAC and half Fiio E09K)
Asus Xonar Essence STXKasso YJ-01 (Basically a better Schiit Vali)
Oppo Ha-1
Gaming Rig: PS4 ⇒ Optical Out ⇒ Astro Mixamp 2013 Edition
Packaging & Accesories
What's In The Box?
The headphones come in well-constructed cardboard box, mostly a matte silver, with thin, shiny streaks running both vertically and horizontally at seemingly random intervals. It looks nice, it feels nice. Inside this nice box you have the headphone case, with the headphones inside of it. A short (1.1m) cable with 3.5mm termination as well as a 3m, thicker, nicer cable terminated with a ¼ in jack. Oppo also includes a Velcro cable wrapper. A nice touch.
The case they include is nice and has a fashion forward design. Definitely a break from the traditional, all-leather-everything styling that we are used to. It is made of selvedge denim, which means it is very durable and, unlike leather, requires no care. The inside of the case in fully felt lined and is minimally padded all the way around. That said, I have kept the headphones in the case, crammed the bunch in my backpack, and proceeded as usual. (That means I threw my backpack around onto tables and into the back seat of my car.) The headphones and case remained completely unscathed.
That said the case is not perfect. The handle at the top is kind of a joke. It is barely wide enough for me to fit my average sized hand into, and it is uncomfortable to do so. Also, the inside of the case contains a felt flap that is supposed to sit between the cups during storage. It has a hard plastic inside that acts as a support beam to protect the headphones from downward force on the case. However, it looks tacky and is not as smoothly integrated as everything else about these headphones. Perhaps I’m just nitpicking.
The cables all use OFC copper wire and the terminations are all gold plated. The headphones use 2.5mm mono connectors in dual entry to get the sound to the cups. This method is among my favorite on headphones because it is tidy, sturdy, and easy to connect and disconnect. The 3.5mm jack on the included short cable is hands down the best I’ve ever used. It is gorgeous, tiny, and feels super premium due to it being all metal. That same style of connector is used on 2.5mm mono terminations on the ¼ in cable. And they are just as sexy.
Unfortunately, on the 3.5mm cable, Oppo opts for rubber coated connectors on the 2.5mm plugs that don’t look fabulous. On top of that, the only way to differentiate left from right on the connectors is from the embossed letters that are difficult to see in most lighting. That isn’t the worst part, in fact, the short, 3.5mm cable is the worst I’ve ever used. I hate it. It is stupidly thin, has tons of memory, and coils itself relentlessly, despite my best efforts. I honestly prefer the cable on the Apple Earpods, or just anything else.
Thankfully, the other cable that Oppo includes is fantastic. The ¼ in plug is big, sturdy, and sexy. The rubberized strain relief blends into the both the connector and cable and looks very professional. The cable runs the majority of its length in a flat and fabric sleeved style that both looks pretty and keeps it tangle proof. Just before the last foot of the cable, we have a fancy metal Y-split that leads us to a good thickness rubber coated wire that is flexible and lightweight. With both cables I experienced no microphonics and minimal cable noise.
Build Quality / Design
Home. Freaking. Run. Honestly, Oppo knocked this absolutely out of the park. Not only do they look gorgeous, but they feel even better. The faux-leather headband is supple, plush, and sturdy. I honestly thought it was real leather until I did some research. The size adjustment mechanism is fantastic, it feels smooth and has strong, positive clicks. The adjustment goes from child sized to insanely large. These will fit anyone. Even with the ear cups fully extended, there are no visible indentations in the metal band, resulting in a sleek look.
Moving a little down the headphone now, we have the hard plastic pivoting mechanism. The cups rotate almost 180°, almost (more on that later). This allows them to be placed flat on the table, in the case, or comfortably around your neck. The rotation is butter smooth with just enough resistance so they don’t feel like they are flopping around in your hand. They just kind of fall into place no matter where you put them.
Sure everything about these headphones is premium, but Oppo really blows it out of the water with the fine details. It’s the little things. The pivoting mechanism does not move a full half turn, rather, it stops maybe a degree or two shy. At first, I thought this was a flaw. Now I realize their reason for this. When the headphones are placed on the table with the left cup on the left, they lay flat. When you flip the cups all the way around and lay them down again, this time with the right cup on the left, they don’t lay flat. They almost do, but they clearly do not. This makes it very easy to keep the cups in the correct orientation, while still allowing comfortable neckability and an option for flat storage.
Just below that pivoting mechanism, we will find yet another fine detail by Oppo. The left cup has a small nub on this portion of the gimbal. You wouldn’t notice it if you weren’t looking for it, but this allows you to find which cup is the left one by feel alone. Yet another nice touch. There is another small nub at the bottom of the gimbal where the cable connects to the left cup. Making it easy to identify the left cup when plugging in the cable. I thought that this was a little gimmicky at first, but I started using both of these nubs on a daily basis the day that I discovered them.
Everything mentioned thus far on the headphones is a gorgeous bean blasted or gray anodized aluminum. The grills, however, are black metal and allow for minimum airflow. They look nice, but we’ll see later if this affects the sound at all (it does). The cups are a sturdy, matte black plastic (probably ABS). While this is plastic, it is not cheap plastic, and the headphones still feel ultra-premium.
Pads / Comfort
These headphones are very comfortable for me. The aforementioned adjustment mechanism is perfect. The pivot mechanism allows for even pressure around my ears. The headband provides what is, in my opinion, an ideal amount of clamping force. The headphones do not move at all with normal head movement, and manage to stay on with some moderate head banging. I’d say they clamp a bit more than average. That said, I have a prominent jawbone and wear glasses but never once had an issue with the PM-2’s clamping force causing jaw pain or headaches, even after a seven hour listening session.
I had the privilege of trying both the stock pleather pads of the PM-2, as well as the velour and lambskin ear-pads. All of the pads have more or less the same plushness. The pads are squishy, yet springy. I originally thought that the pads were made out of awesome memory foam, but turns out the padding is actually latex. Something about longevity and hypoallergenic. All I know is, they are damn comfy!
The pleather pads use the same amazing pleather that Oppo uses on the headband. These pads were very comfortable and I only started sweating after about 3-4 hours of listening. I found these pads to have more energy in the upper midrange than the others while also rolling off the lowest bass notes.
The lambskin leather pads are something to behold. The air holes on the sides are larger than on the pleathers, and it is a tad ugly, but the lambskin is more supple and smooth than the pleather. I could see some folks preferring this, but I did not. I found that, while more comfortable on the head initially, the lambskin pads made my ears and head perspire after only 20 minutes of listening. But they are just so supple. I also found them to tone down the lower treble a bit versus the pleather pads.
With the velour pads, the comfort on my skin is great. While the material is not the softest velour I’ve used, it is far from the worst. I normally dislike velour pads due to them harshening up the treble and decreasing the bass presence in my opinion. But I actually found them to be less bright than the pleather pads and have better bass extension. They were a touch brighter than the lambskin pads, but easily my favorite of the bunch for both comfort and sound.
The pad swapping mechanism is the easiest and most intuitive that I’ve ever seen or used on a headphone. They are held in place but four plastic pegs on the pads that fit into four rubber holes on the cups. A quick pull and the pads pop off, a push on the surface of the pad, and they pop back into place. All told, I can swap both pads in under 15 seconds. It is that easy.
Now onto the bad. The ear cutouts on the pads are on the small side and a bit shallow. I find them to be insanely comfortable, but if your ears are large or stick out from your head a good amount, you might have comfort issues.
The last thing I want to touch on for comfort is weight. The PM-2 is a planar magnetic headphone. It is constructed of mostly metal. They have some heft. They are light for a planar, but still a touch heavy. I didn’t find the weight to be a big comfort issue. The headband is padded with the same previously mentioned latex stuff and it is comfy. I found no hot spots causing discomfort on my head. But my weak neck did suffer after about three hours of use.
Finally! The sound is – definitely not for everyone. It is good. But…
The bass is good. It is clean, it is fast, it is very transparent. While being able to go very deep, there is definitely an emphasis on the upper bass / lower midrange. I wouldn’t say it is rolled off, but the bass has a “fun” tilt to it without being boomy or muddy. On Hans Zimmer’s Why So Serious, every nuance of the other frequencies is preserved even when that glorious sub-bass rolls in. The bass, while good, is not very technical. Often, I find on audiophile-grade headphones, the low notes in electronic music sound unnatural or awkward. The lower frequencies of the PM-2 are quite accurate and quick, but definitely forgiving. For everything from Skrillex’s Remix of Levels by Avicii to the live version of Hotel California by The Eagles, the low notes sound very natural and lifelike. That said, I do personally prefer a more linear extension down low than that of the PM-2, but to each their own.
The PM-2 is a mids-focused headphone to my ears. The midrange is full and lush. So lush that it might turn some listeners off. However, I almost never found the mids to be thick or syrupy.  While the upper midrange is a bit aggressive, the mids remain very intimate and well-articulated. Both male and female vocalists usually sound fantastic. Listening to Taylor Swift, Journey, and Meat Loaf on the PM-2’s is a wonderful experience. Every nuance of the singer’s emotion can be felt through these headphones. Stringed instruments come through with such clarity and life to them. In 2Cello’s rendition of Thunderstruck, I can hear the bows rubbing against each individual rivet in the strings. In Illumination by Globus, I can hear the sound of the strings hitting the fingerboards as the musicians slap their instruments. Pianos sound nothing short of fantastic. In Night Forest, Beshevli uses the slider on the piano to create a sort of background percussion. This is subtly heard through most headphones, but the PM-2 delivers those sounds without removing any intimacy from the lush piano melodies.
Unfortunately, the mids on the PM-2 are not perfect. Some tracks like Styx’s Blue Collar Man and Augustana’s Boston come through just a bit tinny when the singers really start belting it out. Adele’s Someone Like You sounds a tad off, almost nasaly. I can’t quite put my finger on why this is happening, but on some tracks, very few, the mids sound the slightest bit unnatural. That said, I’ve heard nothing short of perfect with every stringed instrument I’ve listened to: from fiddle to upright bass to guitar. That said, every once in a blue moon, a singer sounded a little tinny or thick for a small part of a song.
Everything I’ve said about Oppo’s latest thus far has been very positive. Unfortunately, the treble is the hamartia of the PM-2, its one fatal flaw. While I personally don’t mind the treble presentation of the PM-2, many people will not enjoy it at all. The lower portions of the treble and upper-midrange sound fine. There is nothing special about them. They sound good and clear, while still managing to be a bit unnatural and not the smoothest thing in the world.  To keep things simple, the rest of the highs are completely rolled off. It’s not that they don’t extend well, rather, they are almost absent. The highs are very recessed and sound quite congested. Lifelike hi-hats on Aerosmith’s Love In An Elevator? Not a chance. Nice cymbal overtones on Billy Joel’s We Didn’t Start The Fire? Nope. How about the cymbals having some nice shimmer in tracks from metalcore bands like Bring Me the Horizon? Not even close.
To clarify, you can hear the cymbals. The lower treble and upper midrange is responsible for those sounds. But the rest of the treble is in charge of the overtones. Without overtones, these instruments don’t sound good. The treble is something I could forgive if this was a closed back headphone, but the PM-2 is not. Most every open back headphone I’ve heard has beautiful airy highs that make for very lifelike sound. I love this nice open sound and the PM-2 does not have that. Instead, the recession of the high frequencies makes this headphone sound very closed in and hurts the imaging of certain instruments. While I don’t like this, I can tolerate it given how great the midrange and bass sounds.
I am not a great judge of soundstage, but I know many of you are curious, so I will try my best. The PM-2’s soundstage is quite good. Not massive, but I still had those moments where I would turn my head because I thought someone snuck up behind me, just to find out that it was the music. The sound does not sound in my head, but it sounds around my head. Nothing sounds above or below me, but I do feel surrounded in sound. It definitely does not sound like a planar headphone in this regard.
When gaming, I found the soundstage to be great. Playing The Last of Us: Remastered Edition, the zombies sounded particularly eerie and I could hear their location accurately using the PM-2. When exploring Kyrat in Far Cry 4, the environment sounded realistic and I often heard wild animals long before I saw them. I found the soundstage to be better for side to side positioning than for up and down. I did twice take off the PM-2 because I thought the game audio was coming from my surround sound, but it was just the headphones.
Summary on Sound
During my trial period, I allowed a few of my friends to briefly demo this headphone. One of my friends is an audiophile and Head-Fi’er. He did not like the sound of the PM-2 one bit due to the recessed treble and slightly colored sound signature. However, another friend of mine who is not an audiophile, but appreciates fancy sound systems in cars, gave the headphones what was “the highest praise he could possibly give” by exclaiming, “Holy Schiit! Those sound damn screwing good!”
In conclusion, if you like a slightly colored sound, or if you don’t mind a recessed treble, then you will love the sound of the PM-2’s. If you like very lush mids and solid bass performance, then you’ll like the PM-2’s. If you love hearing the overtones, the shimmer of cymbals, and a nice airy treble. Run.
Here is where I tell you why everyone is looking at the PM-2 all wrong. I often see people comparing the PM-2 to the LCD-2 from Audeze. They hook both of them up to an expensive, all-tube amplifier and compare. The LCD-2 wins according to almost everything I’ve seen. But this is not where the PM-2 is given a chance to shine. I had the privilege of trying out the PM-2 with the Oppo Ha-1, my friends Kasso Yj-01, as well as my own Ha-Info U2 Plus. And much to my surprise, the PM-2 hardly sounds different. Sure, the detail retrieval improves marginally moving up through the amplifiers, but it is about as much of a sound difference as pads are on most headphones. I’m not knocking the Oppo Ha-1, I’m sure it is a great amp. But the PM-2 just does not scale well with great amps. Even without an amp, the PM-2 does remarkably well. Sure, hooked up to an amp it sounds all around better. The bass goes deeper and everything became much clearer and more lifelike. But if I owned the PM-2, I probably wouldn’t spend money on a portable amplifier to use these while walking around. They sound that good without an amp.
I am not recommending that you listen to these headphones un-amped. But don’t expect a dramatic jump in sound quality moving from a $200 rig to a $2,000 rig when using the PM-2.
(This is the DAC/Amp that I used for a good chunk of my tests.)
Final Conclusion
This is a fantastic headphone. All around, I really do enjoy it. It is the best built headphone that I’ve ever seen, touched, or felt. The attention to fine details is remarkable and the headphone looks gorgeous. The accessories are good for the most part. And personally, I absolutely love the sound of the PM-2, minus the congested highs.
It is unfair to compare the PM-2 to other headphones by price alone, since it hardly benefits from quality amping. Instead, I find it more appropriate to compare by rig price. I honestly find my Ha-Info U2 Plus DAC/Amp to be enough for the PM-2. Bringing the cost of the rig that I’ve been primarily using to $773. I’ve racked my brain for other rigs that I’ve heard to compare it to at this price point, but I have only heard rigs far more or less expensive. Let me tell you, the PM-2 sounds more expensive.
As another side note. I find that the PM-2 competes heavily with the Beyerdynamic T90, just with vastly different sound signatures. Lush mids or bright and airy highs? I also find the bass to be faster on the PM-2.
And that’s it. The PM-2 should be the go to headphone for anyone who wants a sub-$1,000 rig with a laid back treble. There is a lot to like about the PM-2, but in the end, if you don’t like the sound signature that I have described, don’t buy the PM-2. If you like laid back highs, or don’t mind them, then seriously consider the PM-2.
Agree fully. These are great phones that aren't the last word on SQ at their price points. They are, however, the last word in comfort and wonderful engineering in the PM category at their price points. I'm 100% satisfied with that.
My music choices tend more towards classical, folk and jazz. When I went out headphone shopping I wanted headphones with an accurate mid-range. I listened to cans from $500-$1500 through Grado, Schiit and Oppo amps. Sennheiser, Grado, Oppo and Audeze phones and, for me, the Oppo's were the only ones that didn't have a muddy midrange. Now, most of the concerts I go to I'm on the stage, not in the audience which definitely affects my perception of what is "right". So, I traded a bit of treble roll-off for a clear midrange.
Excellent review!


1000+ Head-Fier
Pros: Excellent design, looks, and build quality; Works well from about any device; Good bass and midrange, and some improvements over PM-1
Cons: Treble quality is a bit rough; A bit too laid-back in the upper-mids and treble for my tastes; Price and value isn't the best, but also not outrageous
I found a lot to like about the OPPO PM-1, and I was very excited to give the PM-2 a chance based on impressions I had read for it. With the PM-1, the looks, build quality, and overall presentation were stellar. Though I didn’t have a personal need for it, I appreciated that it worked well from about any device, which I can’t say for a lot of other orthodynamic or high-end headphones.
The PM-1 had a smooth, laid-back, warm, seductive sound that was great for long, relaxing listening sessions. However, as I listened more over time, I found it to be missing something. It wasn’t the clearest, most resolving headphone on the market. Despite having good bass extension, it often sounded soft and a bit too light-footed. The treble area was a bit too rolled-off for my tastes as well, though I appreciated the fact it offered zero listening fatigue. In the end, I really wanted to like the PM-1, but it ultimately became a bit boring over time, had too constricting of a sound stage, and lacked a particular sort of finesse that many other high-end headphones offer. Despite the excellent presentation and its ability to work well from about any device, I just wasn’t sold on the price for the sound I was hearing.
After reading the PM-2 would target a similar sound at a much lower price, with OPPO claiming the main audible differences were due to newly developed pads, I was intrigued. As impressions started rolling in from folks I tend to trust, I became more and more eager to give them a shot. Rumor had it that the PM-2 offered a less laid-back, less constricting sound. In other words, it sounded like what I was originally looking for in the PM-1. Sure, maybe it didn’t include a fancy wooden box and used plastic and pleather instead of metal and leather on the headphone itself, but I found that to be more than a fair trade off for the reduced price.
So, how does the PM-2 sound, and how do they compare to some other popular headphones? I’ll get to that in a bit.
Presentation, Looks, Build Quality, Comfort, Etc.
I already mentioned that I thought the PM-1 was stellar when it came to presentation. The premium materials and beautiful box screamed “luxury” and made me want to love the headphone. Alas, it was not meant to be. I was a tad worried the PM-2’s substituted materials might not be up to par with the PM-1, but I was pleasantly surprised. Unless you can compare them side-by-side, the PM-2 still feels like the same luxurious product. The materials seem solid and feel nice, the build quality seems great, and the looks are basically as good as on the PM-1! And while they might not have the same fancy packaging, they still give the feeling of being a premium product. I also like the fabric/denim carrying case they come with.
The PM-1 wasn’t the most comfortable headphone I’ve ever tried. It wasn’t bad, but it could get a bit heavy on the top of my head after a while. This is a fairly common problem for me, though. With the PM-2’s materials, I get the feeling the PM-2 is not as heavy as the PM-1, and it does seem to hurt my head a bit less over time. Maybe I’m just crazy. Clamping force is not too strong either, but it’s easy to bend them to a shape that better fits your head if you have a large noggin. I think most will find the PM-2 to be a rather comfortable headphone.
As expected, the PM-2 works just as well as the PM-1 from a variety of devices. I even found the sound quality to be rather acceptable from my phone. While they do seem to scale with a nice dedicated, desktop DAC/amp setup, I think it’s great that these can be enjoyed around the house or on the go from about anything, even if I didn’t have a personal need for that.
Overall, I give the PM-2 very high marks in all of the non-sound related categories. While I do miss the PM-1’s shiny, wooden box, the PM-2 still looks and feels solid. Very nice!
Sound Quality
Was the PM-2 the improvement I was looking for over the PM-1 when it came down to sound quality? I’ll answer that right away by saying…sort of. The PM-2 comes across as less dark and less rolled-off sounding on the top end. A bit less soft and laid-back. Less constricting in the soundstage. While this seems like it would be an improvement across the board, the PM-2 does take a step or two back relative to the PM-1.
The PM-1 I listened to and measured had a sort of peak around the 10KHz area, and it was fairly depressed relative to the rest of the spectrum due to the rolled-off nature of the headphone. So, they were still laid-back sounding but without sounding totally veiled, as that peak helped give a sense of detail.
The PM-2, on the other hand, has a peak around 8KHz. To me, this is a subjectively worse spot to have a treble peak, because instead of offering extra detail, it gives the PM-2 a sort of raspy, rough, or edgy quality to the treble relative to the PM-1. There are a couple other factors that exacerbate the issue. First, the peak is narrower than the peak on the PM-1, so it sounds less cohesive and stands out more. Second, the PM-2 isn’t as subjectively rolled-off in the treble response, which again makes the treble peak more noticeable. While it generally is not a problem and won’t hurt your ears, as they’re still a laid-back headphone, it does make the treble sound relatively rough and unrefined sounding compared to the PM-1 and other headphones.
Whether or not someone likes or dislikes this, the PM-2 is definitely laid-back in the upper-mids and treble, roughly in the 3-7KHz range. The information here doesn’t go entirely missing, nor does the sound become a whole lot less cohesive or odd sounding because of this, but it does give them a more laid-back presentation relative to some more neutral headphones. Personally, I don’t mind this much, as it makes them much easier to listen to with harsh music and/or over long listening sessions. For example, you might notice in rock or metal that distorted guitars have less of a bite and edge to them, which isn’t always a bad thing in my mind.
The PM-2, much like the PM-1, also isn’t the cleanest sounding or most resolving headphone on the planet. If anything, they sound ever-so-slightly hazy and warm. I suspect some of this is due to their frequency response and some of this is due to some very specific, measurable harmonic distortion characteristics, which I’ll touch on later. That’s not to say they sound “low-fi,” because they certainly don’t. You just might notice a lack of pure clarity across the spectrum and less defined layers in the sound relative to headphones that do better in this category. The soundstage is a bit on the small side, but it doesn’t sound nearly as narrow as the PM-1 did. They’re not quite up to a reference class, if that makes sense.
Subjectively, I felt the PM-2 is still a bit soft sounding, like the PM-1. It could use more kick and a more dynamic sound. That said, the bass is rather balanced, fairly clean, and definitely not accentuated relative to the rest of the spectrum. It only becomes particularly noticeable when compared to headphones that have a more impactful sound, though this can often be alleviated by pairing the PM-2 with a powerful amp.
Now, I will say that the PM-2 often gets tonality down pretty well, they do sound fairly cohesive, and they’re a fairly enjoyable listen once you sink into them a bit. They also do very well when it comes to the midrange. I really appreciate their more laid-back nature, as it tends to suit my tastes rather well. While I do wish the treble was smoother sounding, as they are a step back from the PM-1 in this regard, and I ultimately could use slightly less laid-back upper-mids and treble, I think the PM-2 sounds pretty darn good. Not “excellent” or “reference class” in my mind, but pretty good. They do much more right than they do wrong, and what they do wrong isn’t necessarily offensive and really comes down to personal tastes in the end. I can’t say that about many headphones. At the very least, the PM-1 and PM-2 both offer a lot of encouraging signs about what OPPO might be able to do in the future.
From just a sound perspective, I’m not sure I’d be quite willing to spend the full retail price on the PM-2. However, when factoring in their looks, build quality, and ability to run decently from about any device, that does put them in a more positive light. Even then, I’m still not sure they’re worth the full price given all that for me, but they might be exactly what you are looking for. They do seem to fit an interesting niche in headphones, for sure.
Quick and Rough Sound Comparisons with Other Headphones
I wanted to see how the PM-2 stacked up to some other popular headphones, and just from a sound quality perspective, on a decent, dedicated desktop setup. I had the Sennheiser HD600, MrSpeakers Alpha Dog, and ZMFxVibro headphones on hand to compare with.
I have to admit, when only considering sound quality from a dedicated desktop setup, I found the PM-2’s sound disappointing relative to what you get from the HD600 and HD650 (only did a brief comparison with the HD650, but did do extensive comparisons with the HD600). The HD600 was immediately more engaging sounding, mostly by having a more impactful, heavier sound. The PM-2 was a bit too light-footed in comparison. However, the PM-2 did seem to have better bass quality, as the HD600 can sometimes be a bit thick sounding, primarily due to the 100Hz bump and rise in harmonic distortion down low. Subjectively, despite these traits, I still found the HD600 more enjoyable overall.
The HD600 also clearly demonstrates how laid-back the PM-2 is in comparison. Upper-mid and treble details shine through when listening on the HD600, making the PM-2 sound like it’s missing something. When not doing direct comparisons, this is much, much less noticeable on the PM-2. On the other hand, I actually find the HD600 to be a bit too hot and edgy in the 1-4KHz area for my ears (upper-mid to treble). In that regard, I found the PM-2 more pleasing to listen to, as I actually have to mod the HD600 a bit to lower the response in that area in order for me to listen comfortably over long listening sessions. Going beyond that, I thought the HD600 had smoother, more detailed treble than the PM-2.
The HD600 also had slightly better clarity across the midrange and treble spectrum. Neither of the two are particularly expansive sounding headphones. I thought the PM-2 did a bit better with macro-layering at times, though this was often a toss-up. The HD600 did clearly excel at micro-layering. For example, when listening to orchestral music, the PM-2 would sometimes sound a touch wider and better separated with large musical layers. The HD600 would do a better job enabling me to pick out individual instruments in a tightly clustered group. I also thought the HD600 had a better sense of air.
Now, will the HD600 do quite as well from a wide variety of sources? I don’t think so. That is one big benefit the PM-2 holds. On the other hand, I couldn’t help but be a bit disappointed with how the PM-2 sounded compared to the HD600 overall given the price differential. To be fair, given one can often find the HD600 for around $300, I’m not sure you can really find a better value when it comes to high-end headphones. The HD600 was a big surprise for me when I picked it up a couple months ago, and I can see why they’re so beloved by many. (I can’t speak for how the older Sennheiser revisions sounded.)
Comparing ortho-to-ortho, the PM-2 is even less similar to the Alpha Dog and ZMFxVibro. The latter two are definitely on the bass-heavy side, as they each have a bass boost below 100Hz (though are tunable). This immediately made the AD and ZxV the most powerful sounding headphones of the bunch. Personally, I preferred the middle-of-the-road HD600 approach to this in most cases.
The PM-2 again sounds more laid-back than the AD and ZxV, primarily in that upper-mid and treble region. I thought the ZxV struck the best balance in terms of response in this area with the PM-2 coming in as being the second most preferable here to my ears, even despite their differences. The AD sounded wider and more expansive than any of these headphones, and while it is quite neutral above the 100Hz mark, it has a slightly hard glare and artificial nature to its sound. The PM-2 had the roughest treble of the bunch. Generally, I found I preferred the ZxV and HD600 most out of the bunch, though when not doing direct comparisons, the PM-2 is definitely quite enjoyable. Again, this is from a dedicated, desktop setup.
Measurements and Analysis
After extensive listening, I took some measurements of the PM-2, and I’ll offer some frequency response comparisons as well. If you are interested in learning more about my measurement system so that you can better understand my results, PM me for more info. I do want to say that my measurements are NOT always comparable with other measurements you’ll find elsewhere. It’s best to just compare within my own setup and data. Feel free to share or re-post these graphs so long as you give credit to me.
Frequency response measurements indicate a nicely balanced response from 20Hz-2Khz or so. A tiny bit of extra bass warmth does appear to be evident. The dip centered around 5KHz would explain the laid-back nature I heard in the upper-mids and treble. The 8Khz peak, while mostly in line with the rest of the spectrum, does stand out by being so narrow and in an area that gives the sound a subjectively rough and raspy quality.
Distortion results are overall very good and even push the limits of what my setup can measure. The only thing worth pointing out is the 2nd-order harmonic distortion spikes in the 300-400Hz area, which are a bit odd. This might somewhat contribute to the slightly hazy quality or give a bit of extra warmth, but I doubt this is subjectively problematic or even noticeable in the end. The PM-1 exhibited the same trait.
CSD results are clean in the upper-mids and treble and indicate the PM-2 has no real issues with ringing or resonance in those areas. Don’t worry so much about how they look below 1-2KHz or so, as about every headphone I measure exhibits slow decay there (likely inherent to setup).
Raw measurements indicate a headphone that is pretty consistent with performance and doesn’t rely too much on a perfect fit and seal. With the four raw measurements on each channel, the first two and last two results for each channel are taken in slightly different ways, hence the discrepancies. While I do average these all together in the end, I personally felt the first two raw measurements on both channels best captured how the PM-2 sounded according to how I hear it subjectively.
Frequency response results compared to the HD600 are interesting. Both headphones do things I’m not crazy about. The HD600 has that 1-4KHz rise that bothers my ears, making them subjectively “hot” sounding, and the PM-2 has too large of a broad treble dip for my tastes (the narrow, sharp dip on the HD600 is considerably less audible). That said, the HD600 is subjectively much more lively, smooth, and detailed up-top and is on average more balanced sounding to my ears despite the 1-4KHz rise (this rise is fixable with EASY mods, but this review isn’t the place to discuss HD600 mods). These results also show the HD600 having a stronger response around 100Hz, which explains why they sound more impactful and lively below. (If you’re curious, I took quick measurements of the HD650, not saved, and they had a bit more bass and much less of a 1-4KHz rise…very similar to the HD600 otherwise.)
The Alpha Dog is much bass-heavier than the PM-2 in comparison, though it does have a more neutral response in the upper-mids and treble. The Alpha Dog is certainly more lively and spacious sounding. However, the Alpha Dog does have a slightly “hard” and “glaring” quality to it without felt discs in place, and that small ~6KHz bump may explain things here. I did like the laid-back nature of the PM-2 relative to the Alpha Dog for long listening sessions or with harsher music. (The treble dip on the Alpha Dog is most likely partially a measurement artifact and partially just inherent to how I measure headphones.)
Compared to the ZMFxVibro, the PM-2 is again less bass-heavy, though the PM-2 does seem to have tighter channel matching. Measurements don’t tell everything in this story. The ZxV is a more lush and powerful sounding headphone in ways that extra bass can’t always explain. The ZxV is a bit laid-back in the treble, but still less so than the PM-2, and this is evident when listening to music. The PM-2 seems to have this treble information buried a bit in music. Personally, I generally preferred the ZxV over the PM-2, as it suits my tastes quite well. (The ZxV measurements were done with one tuning vent open on each channel.)
Lastly, here are how my PM-1 (velour pads) and PM-2 (stock pads) measurements compare. I didn't have both sets on hand to compare directly from a subjective perspective, just my data, but some of this is surprising to me based on what I hear on the PM-2 and remember hearing on the PM-1. The PM-1 does show a treble peak around 10KHz vs 8KHz on the PM-2, which is more "detailed" sounding vs "raspy" sounding, and the fact that the peak on the PM-1 is broader means it sounds more cohesive with the rest of the spectrum. Some of the other difference I am not so sure about. I have heard rumors from a few different individuals that the PM-2 might actually have slightly different internal damping than the PM-1, so it might not just be pads making a difference in sound between the two.
If you are interested in additional measurements for comparison, including THD and CSD results, please feel free to PM me. I’ll have a full review up of the Alpha Dog and ZMFxVibro at a later date.
Oh, one last bit of information you might find interesting. I noticed the PM-2 had a better sense of detail and air if I lifted them off my head just a bit, still maintaining a seal, so that the clamping force was effectively lighter. This led me to stretch out and widen the PM-2's headband so it had a "permanent" light fit on my head. They sit very lightly on my head and over my ears now. How did that change the sound? Well, it measurably seems to have filled in that upper-mid and treble dip somewhat, and the treble response overall seems to be better balanced and smoother. And this makes sense, as having your ears closer to a driver tends to reduce the treble response, and more clamp equals closer ear-to-driver distance. This is a quick measurement, one take, of the left channel only. Compare to the left raw 1 and 2 results above for the best idea of how this sounds. Don't worry about the random THD spikes in the bass, as those are artifacts, and ignore the uglier graph.
Maybe I just have a big head, but this quick tweak is worth keeping in mind if you're in the same boat as me!
I think the PM-2 has a lot going for it. It wasn’t quite the big improvement over the PM-1 that I was hoping for, but it is generally a step in the right direction. They have a fairly pleasing sound, do well with tonality, and have a very good midrange response. However, as much as I like a laid-back sound, I think they could use a bit more presence in the upper-mids and treble, and the treble quality is rougher than I’d like. When compared to headphones like the HD600, Alpha Dog, and ZMFxVibro, I can’t help but feel OPPO hasn’t quite nailed the sound just yet…something is just missing that makes me think pricing is still a bit too high on the PM-2. That said, the PM-2 does have many strengths outside of pure sound quality that make me think rather positively of them. For example, if you’re looking for something that feels like a premium product, sounds pretty good in a laid-back way (not excellent, though), and works well from about any device, I wouldn’t have any issues recommending the PM-2. Even then, I think the price is a bit high, but others might consider them to be a good value. I think you could argue it both ways.
I really don’t like giving numeric scores, but from a sound quality perspective, I think these are a solid 7/10 (from a reference perspective, not personal taste perspective). All other areas are a solid 9/10, if not better, in my mind. While I’m hesitant to say these are quite 8/10 material when all things are considered, I suppose I’ll round up a bit in my mind and rate these at a solid 4/5 stars.
You say 'However, as much as I like a laid-back sound, I think they could use a bit more presence in the upper-mids and treble, and the treble quality is rougher than I’d like'
To me PM-2 are nothing like how you describe them, I hear zero roughness in treble, PM-2 have very smooth, extremely low distortion treble. 
Thanx for the effort but did you use the same cable for all headphones ? Did you use the same headphone amp and if so, which ones ?
I think the problem with this review is that it is not from rom a reference perspective, but from personal taste perspective.
Excellent review!