Headphone Reviews

Sound Quality
The overall sound quality of the PM-3 is very good indeed. In fact, it may be the most neutral sounding headphone I've experienced. My previous standard in that regard was the NAD VISO HP50, which in comparison now sounds a bit warm and thick. If the PM-3 does deviate from neutral I'd say it had a bit of extra upper-bass/low-mid energy, a bit extra lower-treble, and is slightly rolled off in the top octave. I heard it as very slightly "U" shaped due to the slight upper-bass/low-mid and low treble peaks...initially.

A slightly "U" shaped response means it should sound slightly exciting, but somehow they just don't to me. If anything, they sound slightly boring...again, just slightly. Problem is, for quite a while I really couldn't figure out what was going on that might give me that bland impression. The bass hits hard; mid-range is very well behaved with low distortion; treble seemed slightly forward in the presence region and slightly laid back in the top octave. But there was nothing blatantly obvious that I could figure out.

Then, I was listening to Rickie Lee Jones album "Pop Pop" to the track "Dat Dere" and 18 second in the drummer starts some soft brushwork on the snare in the background. I was switching back and forth between the NAD VISO HP50 at the time and, BAM!, it hit me: The brushes on the snare sounded more withdrawn to me on the PM-3 than on the HP50. In words, I characterize this like the difference between "sss" and "th". In numbers, I'd say we're talking about the 4-8kHz region being a little subdued.

This 4-8kHz region can be really horrible sounding if over-accentuated—think piercing sibilance that makes you wince. I've also seen headphones (Philips X2) in which this area is intentionally reduced to make the headphones more pleasant to hear, and it does seem to take the edge off harsh recordings. I wouldn't characterize this as a big problem in the PM-3 because it means they're not strident—even though their presence region (say 800-3kHz) is a bit forward. But having it (4-8kHz) lay back 2-3dB does have it lacking just a little bit of liveliness for me.

This is a bunch of nit-picking though, for the most part the PM-3 frequency response just sounds straight down the middle. You may have seen my article with a first pass of applying my interpretation of the Harman target curve as compensation. (I say my interpretation for two reasons: The only published curve is Harmans first pass on the subject and not a final official target; and after I eyeballed their curve onto a spreadsheet and started to make the comparisons I found everything was showing too much treble in the top octave, so I did slightly adjust the high treble.) The following frequency response plot of the PM-3 is compensated using that target response curve.

For reference, I'll also post the Harman response curve (in black) here.

The thing I'd like to point out is the gently rising section of the curve from 200Hz to 800Hz. Most headphones are flat, or even falling, in this area. What I hear on the PM-3 is that vocals have a very power presence to them. I hear a better balance between the singer's fundamental tone and the overtones of the voice giving it more strength. There also seems to be a better balance between the voice and the noises made by the mouth and throat—lip smacks, spittle in the throat, air passage through the nose, etc. Switching back to headphones without this rise seemed to deliver voices that were more distant sounding and less rich with information that made the voice organic and powerfully human. I'd love to hear from readers who might be able to make this comparison and express your experience with vocals. This sound is not common with headphones, so it's a bit new to me as well and feedback would be very interesting.

Outside of neutrality, the PM-3 has good dynamics and imaging, but I wouldn't call it great. They're a sealed can and bound to sound a little closed in, but I'd say they image fairly well for a headphone in that category. Dynamic impact is a stronger suite for the PM-3; bass it tight and undistorted and they've got plenty of snap when called for. I also noticed when switching from my HeadRoom Max Balanced Amp—which I use for basic comparisons due to its 4 outputs—to the Simaudio Moon Neo 430HA, dynamic impact (and everything else, really) improved significantly. The PM-3 does scale well (respond well to improved upstream gear). The PM-3 also does a very nice job of remaining clean sounding at loud levels.

In comparisons with the Oppo PM-1/2, I did find the PM-3 to be the more tonally correct, but the PM-1/2 had a more airy and open sound. Personally, in terms of sound quality, I think I prefer the PM-3 to the other two models.

In comparisons with other cans of this type (NAD VISO HP50; Focal Spirit Pro; Shure SRH1540; Audio Technica ATH-MSR7) I found the PM-3 to easily sound the most neutral, but all but the Focal sounded more lively and open. Varying tastes among enthusiasts will have to decide which suites best, but audio pros should probably go straight for the PM-3.

Summary
I don't think I've ever had a headphone come through the lab ticking so many boxes so confidently. Sound quality, styling, comfort, build quality, isolation, and accessorization are all very well executed for this price. The Oppo PM-3 may be the most well rounded headphone offering I've seen to date.

On the other hand, it's a bit like going to a party with the honor roll students—straight A's and across-the-board competence can feel a little boring. A little missing info mid-treble and in the top octave has the PM-3 sounding just a bit laid back and closed in. Fortunately, a near ideal response, in my opinion, between 500Hz and 3kHz, delivers vocals with an organic balance I've rarely heard before. All-in-all, though lacking in that last bit of refinement and air (that's generally reserved for open acoustic headphones), the PM-3 is an extraordinarily competent sealed headphone.

You betcha the PM-3 is going up on the Wall of Fame. It's going to knock off the Focal Spirit Professional, which seems to me the weakest on the page at the moment. I'll keep the SRH1540, HP50, and MSR7 up as they all have better resolving power. (The M100 stays for its basshead nature.)

Video
Click here if you can't see the video.

Resources
Oppo Digital home page and PM-3 product page.
Head-Fi Reviews and threads here and here.