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OPPO PM-1 Planar Magnetic Headphones and HA-1 Headphone Amplifier Review

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OPPO PM-1 Planar Magnetic Headphones and HA-1 Headphone Amplifier Review

OPPO Website
PM-1 MSRP: $1,099
HA-1 MSRP: $1,199
Available Direct From OPPO.

by Wayne Myers


OPPO is the company that makes the Blu ray players that will play anything, right? Well, they are branching out. They have recently introduced products that take them in one new direction that is not surprising at all and in another new direction that you might not have expected.

The more surprising product is the PM-1 Planar Magnetic Headphone, intended for the critical listener. The more expected new product is the HA-1 Headphone Amplifier/DAC. Of course they were going to come out with a high-performance DAC at some point. The HA-1 is an asynchronous DAC wrapped up with a discreet, fully-balanced, class-A headphone amplifier, along with every imaginable input type. The product says OPPO all the way - super-versatility, first-rate performance, impressive quality, and a surprising price - and combined with me PM-1 headphones creates a serious personal listening environment.


The OPPO PM-1 is an around-the-ear, open headphone designed for the serious music listener, a planar magnetic design in a simple yet elegant package. OPPO chose not to slap you in the face with their brand on this product. I almost needed a flashlight to find the lightly etched logo, model number, and serial numbers, opposite of the way most 'phones are branded these days. The headband and ear pads are covered in soft leather, and these headphones are supremely comfortable, with just enough adjustment range. The tightness amount was perfect for me just sitting and listening, but just loose enough for them to slip off backwards if I got up quickly.

They fold flat, not super compact but compact enough to easily fit in a backpack or large purse. I would want a little extra protection for the leather ear pads, they seem like they could be easily torn by a sharp object competing for space while being transported. Good thing they come with a tough denim-covered travel case big enough for the phones and cables. Once zipped inside, they are quite compact and very well protected.

The PM-1 design looks reasonably durable, not as tough as some studio headphones made to take a severe beating, but tough enough for the kind of use most people put their "special" set of headphones through.

The cable is cloth covered, up to the last foot of its length, where it splits to two plastic cables and a separate mini plug for each ear piece. The mini plugs were clearly marked and plugged firmly into the headphone earpiece with a healthy click to tell you it was seated properly and would not pull out with a little accidental tug. The standard cable appears to be wired with separate ground conductors down to the 3-conductor 1/4-inch plug. Also included is a similar but lighter and shorter cable that terminates to a 1/8-inch plug for use with phone or portable player. An optional cable is available with termination to a 4-conductor connector, supporting fully-differential operation from signal input to earpiece.

The PM-1 comes with a beautifully-finished wood storage case that is almost a small piece of furniture, a sure attention-getter. A pair of velour-covered earpieces is also included for those who prefer that feel over the leather.

The HA-1 headphone amplifier is a fully differential amplifier design employing hand-picked and paired discrete power devices in the power amplifier stage. Once the signal leaves the DAC, it stays in the analog realm right through the motor-driven precision volume control. The Class-A design runs hot, so no stacking, one must respect its need for good ventilation. The user who has never been around a Class A amplifier might be alarmed by this. My evaluation unit was very hot after several hours of idling, and that is how it goes with class-A amplification where devices have a relatively high bias current running through them constantly to keep them in their most linear range of operation.

OPPO designers were thorough about providing all possible popular input and output possibilities for the HA-1. There are single-ended and differential analog inputs, and the same complement of preamp outputs. Digital inputs include USB, which will require driver installation on the computer side, TOSlink optical, SPDIF coaxial, and AESEBU-balanced digital. A front-panel USB port allows attachment to an iPod, iPad, or iPhone device as a music source. Also possible is easy Bluetooth pairing and aptX-capable streaming from any tablet or smartphone.

The front panel is simple and highly functional. A beautiful multifunctional 4.3 inch color display is accompanied by the precision volume control, the input selector switch (which also switches display functions), and the headphone connectors.



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Unboxing the PM-1 and HA-1 helps prepare you for the listening experience to come. The packaging and design are statements of luxurious elegance for the PM-1/HA-1. One small box holding cables and accessories, itself attractively covered, was inside a soft cloth bag.

The PM-1 have a laid-back high end and a very deep, very flat bass response, an overall very smooth-sounding profile, and are also extremely fast and clean. They are made for extended listening without listener fatigue. Where many headphones reach out and grab you with a unique sonic signature, the PM-1 have a neutral, do no harm presentation, almost daring you to find something to be annoyed with about them. My only disappointments with the PM-1 were that I found myself adjusting the 'phones position on my ears to get the most treble possible, and the soundstage was not very wide on some tracks.

The PM-1 had a way of revealing distortion, too. More than once I heard lower levels of distortion on recordings I was very familiar with, and went on a chase only to find it was in the original recording but my other reference headphones simply never brought it out like the PM-1 were able to. The somewhat brighter models I am used to probably tend to mask that distortion.

While I enjoyed most of my time with the PM-1, I was waiting for that moment when a threshold gets crossed and they go on my "gotta have them some day" list, but that never quite happened. I expect that with a slightly brighter high end it probably would have, because they are a very neutral and accurate-feeling headphone and do what they need to to not get in between you and your music.

The HA-1 USB DAC drivers download and installed easily with no parameters to select. The unit is almost plug and play. Plug in power, USB cable, and headphones, and start listening.

I downloaded the free HA-1 app from the Google Play store for my Android tablet that acts as a remote for foobar2000 via the FoobarConPro app, and the two apps and HA-1 remote worked flawlessly together for their overlapped volume, forward, reverse, pause, and play functions. I liked holding the tiny HA-1 remote in my hand while listening. Its tactile buttons were easy to operate with eyes closed.

I did not get a chance to operate the PM-1/HA-1 in full differential mode, supposedly an important part of the ultimate headphone listening experience. I have done so in the past with a computing product set up for A/B testing between the standard and differential setups. The difference was notable and certainly enjoyable, giving a wider presentation and a more open soundstage. For me it was not a "gotta have it" difference.

Headphones wired with separate ground conductors all way down to the three-conductor plug will probably give 80% of the benefits desired in a fully-differential configuration.

The PM-1/HA-1 duo is capable of delivering SPLs of 105 dB average with 15-dB-dynamic-range recordings, yielding peak SPLs of 120 dB. That seems like plenty to me.

The HA-1 analog performance specs approach the realm of being ridiculous, but that is part of what high-end audio us all about. If there is a chance in a billion that one freaky set of golden ears might ever be able to hear some level of distortion, the spec must be 100x better than that. Just remember that it is all good, clean fun and that we enjoy arguing about it almost as much as we do listening to it.

PM-1 Headphone Measurements

PM-1 bass response is very flat and goes clear down to 20Hz, Upper-mids and highs are somewhat laid back.

PM-1 distortion is very low. My measuremants at 80 dB SPL showed <0.5% at 30 Hz, <0.2% at 50 Hz, and <0.1% at and above 100 Hz (except for a few little 0.2% to 0.3% peaks between 100 Hz and 330 Hz, which showed up consistently.)

Impulse response shows only minor ringing at the transducer resonance point, and a fast die-out of that ringing.

Step response diagrams show fast response, minimum overshoot, overall very fast recovery times for the PM-1 transducers.

Individual Test Scores

Measurement Methods

Go to the Headphone Roundup Overview for scoring and comparison details.

  • Test Scores
    • Very-High-Frequency: 9
    • High-Frequency: 9
    • General: 8
  • Weighted average (x1, x1, x2): 8.5
  • Weighting in Overall Performance Score: x2
  • Test Scores
    • Bluegrass track: 6
    • Funk Band track: 8
  • Average: 7.0
  • Weighting in Overall Performance Score: x2
  • Test Scores
    • Cymbal, loud track: 10
    • Bass, loud track: 10
    • Cymbal, quiet track: 10
    • Cymbal, loud track: 10
    • Strings, loud track: 10
  • Average: 10.0
  • Weighting in Overall Performance Score: x2
  • Test Scores
    • Deep bass track: 10
    • Lows track: 10
    • Mids track: 10
    • Upper-mids track: 10
    • Highs track: 10
  • Average: 10.0
  • Weighting in Overall Performance Score: x2
Frequency Response
  • Frequency Response Profile: Tilted
  • Test Scores
    • Deep bass track: 10
    • Lows track: 10
    • Mids track: 10
    • Upper-mids track: 10
    • Highs track: 10
  • Average: 10.0
  • Weighting in Overall Performance Score: x4
Overall Listening Experience
  • Score: 8
  • Weighting in Overall Performance Score: x4

Listening Tests

Imaging: 8.5 - Imaging with the PM-1 was quite good, although not stellar. It was always very stable, no smearing or wandering, but was a bit soft at mid frequencies.

Soundstage: 7.0 - The soundstage varied from quite good on some tracks to quite narrow on others. It was relaxed and natural, but the sensation of the soundstage moving out of the head and in front of me took awhile and was not fully engaging and convincing.

Clarity: 10.0 - Here the PM-1 stole the show. They were so clear that I was hearing distortion in familiar recordings for the first time. It was the nature of the PM-1 to be very revealing of inner detail like that.

Speed: 10.0 - The PM-1 handled these test tracks perfectly. Planar Magnetic technology is known for its responsiveness. The impulse and step response tests also show low amounts of ringing and fast recovery times.

Frequency Response: 10.0 - Frequency response is very smooth, tilted downward above 1 kHz. Although more laid-back than I prefer, it was so smooth and unobtrusive that I chose to give it a perfect score here and subtract a point from the "overall listening experience" score to note my personal preference.

Track Hopping

The Shins - Port of Marrow, all tracks - This superbly-recorded album literally begged to be heard from beginning to end on the PM-1, and was a delight to hear with their simple, honest clarity of presentation. I liked the way they brought out a slight liquid edge in the way James Mercer's lead vocals were recorded. Every track had subtle sonic detail held in reserve for a revelatory delivery device like the PM-1 to unlock. They pull apart the density of such a recording, allow the listener to hear the almost-invisible sounds in between the sounds. Had the PM-1 been graced with a couple dB more upper mids and highs above 1 kHz, I have no doubt they would have enslaved me and the "gotta have them" threshold would have been crossed easily while hearing this album. The beautiful chorus on 40 Mark Strasse got several plays at high levels - the PM-1 and HA-1 can deliver peak SPLs around 120 dB with average SPLs approaching 110 dB on a low-dynamic-range track, and never make the volume level obvious by distorting.

Tesseract's progressive metal Altered State album got sampled with the PM-1/HA-1. Bass response with the PM-1 is flat and deep. Those who insist on emphasized bass might find this a disappointment, and with flat 'phones that drop off below 50 Hz, the bottom end can seem weak. The PM-1 bottom end JUST begins to droop at 20 hz, and tracks with low bass content like many on this record are likely to teach one a new appreciation for flat, DEEP bass. This music also invites one to nudge the volume higher and higher, and it stays so clean it is wise to glance at the color display once in awhile and monitor levels for safety.

Nickel Creek - Ode to a Butterfly - This old favorite revealed the narrowness of the soundstage. Mandolin and guitar, usually just inside the left and right speakers, almost came from points side by side via the PM-1, all four acoustic instruments crowded onto a tiny stage shoulder-to-shoulder.

B-52's - Ain't It A Shame - Also a prime test track. The wide synth parts came from fairly wide points left and right, but the nearer-in instruments were all crowded together close to the center of the mix. The PM1-redistributed soundstage was not a favorite point for me. The distorted vocal at 3:24 - "your color TV" - was the first example of recording distortion that the PM-1 revealed.

Tower of Power - Fanfare, You Know It - Here the soundstge felt wider. The PM-1/HA-1 treat horns and brass right, and the big band sounded great on them.

Cincinnati Pops Orchestra - Introduction to 'Also Sprach Zarathustra' (From 2001 & 2010) - altered version; Cincinnati Pops Orchestra - Star Trek (the movie) - Main Theme - The big, beautifully recorded orchestra sounded great on the PM-1/HA-1. Here the soundstage was wide and well distributed. The bells and cymbals on the second of the tracks stood out with a nice balance. The detail and clarity of the violins was very nice, never got buried or strident on the hotter passages on this track.

Joni Mitchell - California - Joni's voice sounded as perfectly represented as I have heard it on a any speaker or headphone. The PM-1/HA-1 are all about truth without hype.

Radiohead - Weird Fishes--Arpeggi The four drumstick lead-in clicks can tell one a lot about imaging. Fairly tight with the PM-1, they should well be tighter, should be mere pinpricks of images.

Devin Townsend - Disruptr - I definitely missed the hotter high end on this track's cymbals.

Overall Listening Experience: 8 - For all those good qualities, I had to subtract a point for the highs being a little more laid back than I like combined with the narrow soundstage, and another because the PM-1 never pulled me over the "gotta have them" threshold. That said, I enjoyed listening with them very much. Their "do no harm" clarity and smoothness should appeal to listeners with a preference for an accurate and transparent, although somewhat laid-back, presentation.

Non-Listening Scores
Comfort: 10 - Supreme, luxurious comfort is what you get with the PM-1. Contact pressure is perfect, but be careful if you move around quickly, or they might slip off.

Design: 9 - The design is simple and sturdy. The PM-1 are attractive headphones that do not stand out or show off. One has to look close to find the OPPO brand - an understated confidence on OPPO's psrt. I held back a point for the 'phones because I wanted something about the design to grab me, not be quite so laid back (as with the high-frequency profile). All accessories and packaging cried out for that 10/10 score - cables, gorgeous high-gloss storage case, denim travel bag, remote, and more... but I could not shake the feeling that the design of the headphones themselves, although very nice, was slightly generic.

Overall Performance Score: 9.0 out of 10

Other Factors - not part of the Overall Performance Score
  • $100 reference headphone: No
  • Drivable with portable media devices: Yes. PM-1 are quite sensitive and can be driven by virtually any media player or amp.
  • Isolation (if closed design): n.a.


The OPPO designers outdid themselves with the HA-1 design. There is absolutely nothing I could imagine wanting that they did not include, and did so absolutely beautifully. It is a marriage of no-compromise audio performance perfection with everything-you-can-think-of-functionality and a "Yeah we thought of that, too" user interface. The HA-1 should be high on any audiophile's list of Headphone Amp/DACs for audition.

The PM-1 planar-magnetic headphones had many really strong points, excelling with their clean, neutral presentation and speedy response. I only hold back slightly for its laid-back high end and a bit more for its somewhat narrow soundstage on some tracks. But the PM-1 is worth considering where a neutral, clean "window" into the music is required.

The HA-1 Headphone Amp Pros:
  • Stellar audio performance specs.
  • Analog signal path stays analog after leaving the DAC, precision motor-driven volume control.
  • Every input type you can think of.
  • Well-thought-out user interface.
  • Color status/metering display.
The HA-1 Headphone Amp Cons:
  • None

The PM-1 Planar Magnetic Headphone Pros:
  • Smooth frequency response.
  • Deep, flat bass.
  • Extremely low distortion.
  • Fast response drivers with little overshoot or ringing.
  • Luxurious comfort second to none.
The PM-1 Planar Magnetic Headphone Cons:
  • High frequency response a little too laid back for my taste.
  • Soundstage compressed on some tracks.

PM-1 Planar Magnetic Headphone Performance Summary and Overall Performance Score
  • Imaging: 8.5
  • Soundstage: 7.0
  • Clarity: 10.0
  • Speed: 10.0
  • Frequency Response: 10.0 (Tilted Profile)
  • Overall Listening Experience: 8
  • Comfort: 10
  • Design: 9
  • MSRP: $1,199
  • Overall Performance Score: 9.0 out of 10

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