Introduction
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!
Conclusion
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.