We've reviewed a bunch of headphones over the years, and what they all had in common were traditional, commonly used voice coil dynamic drivers as a means of producing sound. But very few headphones use a driver technology that's called "planar magnetic drivers", which are large thin diaphragms sandwiched between magnetic grids that use all of their surface to produce sound, don't have two moving parts like dynamic drivers, and have an ultra-fast transient response. You'll only see these being used on high-end, expensive headphones from companies like Audeze and HiFiMan. Another brand that prides itself in using planar magnetic drivers is Oppo, a company you may not immediately recognize or associate with audio at all. Oppo's PM-3 are the company's entry-level over-ear headphones which use planar magnetic drivers to produce high quality sound that's more accurate and has less distortion than other similarly priced headphones with typical dynamic drivers. So how does a $400 pair of planar magnetic headphones sound like? You can check out our full review down below to find out! 

Oppo packages the PM-3 headphones inside this dark gift box-like packaging with the headphones already folded and tucked flat inside an unusual looking protective hard shell case. And I say unusual because this travel case has a denim-esque fabric texture to it like a pair of dark jeans. Styling aside, this is a really nice travel case that will protect your headphones very well.

Also included inside a draw string bag is a 3-meter long straight detachable audio cable with a screw-on 6.35mm adapter.  The PM-3 also come with your choice of a portable audio cable with support for iPhone or Android devices.

This cable is shorter at 1.2-meters and features an in-line 3-button remote and microphone for controlling your music, volume, and calls. It works great and buttons can easily be identified with the sense of touch. Both cables are tangle-free, color matched to the headphones (white or black only) and have slim aluminum 3.5mm connector plugs, which is always a nice touch.

While not the prettiest of headphones and are somewhat uninspired and generic looking, Oppo’s PM-3 still have some form of elegant charm to them and have a better looking contemporary design than a lot of other audiophile headphones out on the market today.

The build quality is underwhelming. And I say this because when you're paying $400 you should expect the very best in materials. And the fact that the headband and ear pads are made using faux leather is unacceptable. It cheapens the overall feel of the headphones and it just isn't as satisfying at this price bracket. Every single headphone at this price is made using the highest materials and build quality including the use of lamb skin leather. The synthetic materials of the headband and ear cups feels incredibly cheap and smells of horrible chemicals.

It's a shame because Oppo did a great job making the PM-3 feel very sturdy with those amazing aluminum hinges, strong metal frame, rigid headband and nicely finished aluminum ear cup accents. Although the ear cup housings are made out thick, matte finished plastic instead of aluminum like the H6 and MH40 headphones. That said, compared to similarly prices headphones like the B&O BeoPlay H6, Bowers & Wilkins P7 and the Master & Dynamic MH40, Oppo's PM-3 aren't even close in matching that same level of premium build quality and design.

For a closed-back style over-ear headphones the PM-3 do have a considerable amount of noise spill. That means although they provide decent isolation from the outside world, they leak out some of the sound you're listening to at normal volumes. Enough to be picked up by anyone that is sitting next to you. So be sure to keep that in mind when you're considering these headphones for travel purposes.

Clamping is very strong on the PM-3, however, they continue to feel comfortable when worn for long periods of time. Those large over-ear cups and thick ear pads help make wearing the PM-3 a great pleasure. I will say that I still prefer the B&O H6 as they don't clamp the sides of your head as much and are noticeably lighter too. My ears feel like they're being hugged tightly by the PM-3, and while I don't find it to be uncomfortable, I can easily see how that might be irritating and even fatiguing to some.

We know that the PM-3 aren't exactly impressive when it comes to feeling like a premium $400 pair of over-ear headphones, so they should at least sound like they're worth this much. Right?After all, they do have planar magnetic drivers inside. Well, I'm disappointed to say that I was unimpressed by the PM-3's overall sound performance. The PM-3 sound acceptably detailed and have relatively clear sounding highs, but next to the Audio Technica ATH-M50x - highs aren't as polished, bass lacks definition, deep lows are non-existent, and the midrange sounds cramped and dark. When a headphones that cost less than $200 outshine headphones that cost more than twice as much...you're doing something wrong. It's not like the PM-3 have an epic design and build quality so sound was their last resort. And sadly, they haven't wow'd us with their audio prowess. With that being said, the Audio Technica M50x may sound better, but the PM-3 have a higher build quality and are arguably slightly more attractive. 

I noticed that even though Oppo says the PM-3 can be easily driven by a smartphone, they do require more power than ordinary headphones even when used with the iMac. Using these with an iPhone I had to turn my volume halfway until I reached a volume that started to sound good when I would normally be listening at a third of that with all other headphones, especially the M50x which are highly sensitive.

If you've never listened to other headphone and picked up the PM-3, then yes, you would think they sounded incredibly good. With so many other great alternatives to choose from, Oppo's PM-3 aren't close to being worth their asking price.

Of course next to the Bang & Olufsen BeoPlay H6, the PM-3 make them sound flat and boring with their much fuller and richer sound signature. The H6 don't sound bad, and actually produce superior sounding midrange, they just lack a lot of bass and some people like that flat response. I absolutely love the build quality, design and the amazing comfort of the H6, but they sound awfully bland and more like a pair of $100 headphones compared to the M50x.  

Are the Oppo PM-3 the best sounding headphones under $400? We think not. Not even close. In fact, you shouldn't even consider them at this price point. The PM-3 offer nothing in return for your $400 other than mediocre sound and fake plastic leather. Instead, consider the Bowers & Wilkins P7 or Master & Dynamic's MH40 if you're looking for premium quality over-ear headphones with incredible sound qualities. Or you can get the best bang for your buck with one of the best sounding headphones for under $200 with Audio Technica's ATH-MH50x.

Oppodigital.com