julio 14, 2024

Revisión: auriculares internos Master & Dynamic MW09, tranquilizadoramente sin cambios

Having been a long-time on-ear headphone guy for mobile use, it was Master & Dynamic who persuaded me to switch to in-ear headphones for everything except flights. Five years on from the MW07, the company has just launched its third-generation model, the MW09.

If you’re in the market for a new pair of in-ear headphones, and are willing to pay a hundred bucks more than AirPods Pro pricing for a whole new level of audio quality – with a couple of important caveats – read on …

The mobile audio compromise

When it comes to pure audio quality, there are few who would dispute that in-ear headphones come a long way down the pecking order. From best to worst:

  • Open-back over-ear
  • Closed-back over-ear
  • On-ear
  • In-ear
  • Bone conduction

But when it comes to mobile use, there’s a trade-off between audio quality and convenience or practicality.

You can’t use open-back headphones on the street, or public transit, without annoying anyone close to you. Over-ear headphones are bulky, so not the most convenient option for everyday use, even if they fold.

For many years, on-ear headphones were my mobile compromise. Good enough sound quality, workable enough portability.

It was testing the Master & Dynamic MW07 which shifted the equation for me, coming close enough in quality to my trusty B&W P5s that I was willing to sacrifice the relatively modest difference in audio quality for the massively more convenient form factor.

The MW08 Sport further boosted convenience by supporting wireless charging, and the MW09 brings that benefit and other improvements across all variants.

Two kinds of people can stop reading here

Much as I remain a fan of the in-ear headphones in this latest iteration, there are two categories of people who should not buy them.

First, if you already own the 2021 MW08 Sport, the improvements the company has made in this model are really too small to justify an upgrade. The latest version of the company’s noise-cancellation offers a noticeable but not dramatic improvement in ambient mode. You also get more control over the sound profile – of which more later – but given I prefer the neutral one you already have on the MW08, that’s something I consider irrelevant.

Second, if voice calls, not music, are your primary usage. Apple seems to be one of the few companies on the planet that has figured out how to make in-ear headphones with decent performance for voice calls – namely, you have to move the microphone outside the ear. Like almost every other in-ear headphones I’ve tried, the performance of the MW09 for phone calls remains in the barely adequate range.


The form factor of the MW09 is similar to the MW07 and MW08 before them. The most distinctive feature of the previous generations was a flat D-shaped exterior. The MW09 retain this, but there’s now a very prominent circle within the D, with the Master & Dynamic logo.

As someone with very minimalist tastes in design, I personally prefer the older design, but sometimes people just want to switch-up the look.

Aesthetically, I also preferred the original stainless steel casing, but the introduction of wireless charging was a good reason to change, and the plain black is a good substitute.


I do seem blessed with standard-sized ear canals, as I rarely find a problem with the fit of any in-ear headphones, and the standard Master & Dynamic tips have worked well for me each generation. This is again the case, the fit being both comfortable and secure.

However, I’m told that they weren’t always as secure for everyone, and that the new sets of tips provide additional flexibility to suit different anatomy.

The companion app includes an automated test to confirm that the fit works from a noise-sealing perspective, and the standard tips passed that test for me.


The MW09 have the same controls as on previous versions. Two separate volume buttons on the left earphone, and a multifunction button on the right. Press once to play/pause, twice for next track, three times for previous track and hold down to activate Siri.

This time, the volume buttons also double-up as ANC toggles. A long press on either button switches between the current and previous setting. I’m not sure why this doesn’t cycle through each of the settings, but since I leave ANC enabled and only need to toggle ambient sound on/off, this works fine for me. Those who need to eek out battery life for longer periods (see below) by toggling ANC on/off as well as needing ambient sound might find it a bit frustrating, however.

Audio quality

I said above that the MW07 were the first in-ear headphones to pass the ‘good enough to switch from on-ear headphones’ test.

Master & Dynamic argue that each successive generation has further improved on the audio quality, but I’d be lying if I said I could hear a difference. Indeed, to me the best thing about the MW08 and MW09 is that they didn’t mess with the sound profile.

With my MW08 review, I took the lazy but accurate approach of simply quoting what I said about the MW07 sound quality, and as hard as I might try to think of something new to say this time, the truth is that everything I said back in 2018 still applies to the 2023 model.

The audio is beautifully neutral, especially noticeable in live performances where you can really feel you are there in the room.

Both treble and mid-tones are clear and detailed, and the bass is really impressive. But while the bass has real presence, it doesn’t feel in any way artificial – the balance is spot-on.

There’s also plenty of volume. Even on public transit, I never use them at maximum volume, which I think is another impressive achievement from in-ear units. But if you do crank them up to the max, there’s no distortion.

For pure audio quality, these are hands down the best in-ear headphones I’ve ever used.

Should the neutral sound not be to your tastes, you can choose a different preset or custom sound profile in the companion app – but I’m betting you won’t want to.


There are three flavors of active noise cancellation: Max, All Day, and Adaptive. Max does what it says on the tin, while All Day is a more modest form, offering a compromise between performance and battery-life. Using Max reduces the battery life from 16 hours to 12, but it’s hard to imagine needing more than that unless you are camping and don’t want to over a power bank – and if you’re going that far back-to-nature, do you really want music in your ears all day?

Adaptive ANC works, but honestly I just stick to Max.

Battery life

I typically use in-ear headphones for a maximum of 3-4 hours a day, usually less. My most demanding usage is long-haul travel, but even then I’ve never hit the 10-hour limit of the previous model (with ANC on).

However, I did use them on successive days without recharging, and with ANC on hit a total life of just under ten hours of the claimed twelve.

Pricing and conclusions

If you’re an audiophile, you won’t be using in-ear headphones period (and probably not listening to music on the move in the first place). Conversely, if your ears don’t go beyond AirPods Pro level, then be happy and buy those.

I’m between the two. My ears aren’t audiophile grade (thank heaven!), but I can certainly hear the difference between AirPods and these. If your ears are similarly mid-range – even if you are so far convinced that on-ear headphones are as far as you’re willing to compromise when it comes to mobility – I highly recommend giving the MW09 a try.

Master & Dynamic MW09 are available from the company’s own website for $349 (aluminum case) or $399 (kevlar case).

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