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


Introduction

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.


Description

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.



Specifications



Impressions

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



Listening Tests

Non-Listening Scores

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.

Conclusions

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