These are the latest headphones from PSB, the M4U9’s and I’ve really enjoyed using them. Let me run you through everything.

They come In a big box and it’s quite a nice unboxing experience. Put aside all the bits and pieces, the headphones themselves come in a pretty robust, large, high-quality hard case. Larger than average so something to consider if you’re putting these in a bag for your daily commute. It’s zipped, it’s got a Velcro storage section inside for any cables and/or the spare earcups, and holds the headphones securely in place.

If you’ve used PSB headphones before or seen them, you know what their image is and these are in keeping with that, although looking online at other models, these do look more refined and premium. Matte black in colour, some hints of chrome and glossy black and this is the only colour they come in.


Thick sponge to both the ear cups and adjustable headband. Lots of flex and adjustability to allow a fit that should suit most heads. The earcups can be removed and you are provided with a spare pair in the box. It’s a little fiddly and you need to use a lot of force to get them off. Each cup is clipped into place with little notches all the way around and although that makes them very secure, it felt like I was going to break them when taking them off.

All the controls are located on the right ear cup and they include power on and off, ANC, volume, track and Bluetooth control. The controls work well, I really like the rocker switches for the volume and track control, they’re very smooth. Each button is well positioned and I found them very easy to use on the fly.


Let me touch on the specifications before I go on to performance. We’ve got Bluetooth HD connection with aptX adaptive and cVc technology. Graphene-infused 40mm drivers, which I’ve not heard of before. Closed-back, over the ear and amplified sound. Separate active noise cancelling, active and passive modes. Roomfeel, which is PSB trademark for sound profiles I believe. Personal sound by Audiodo, where via the app, the headphones adjust to suit your hearing. The app also offers other settings and updates. Run time of 25 hours in active mode and all for the retail price of £449 here in the UK. 

As for performance, superb. I’m no audiophile but I do try out a lot of headphones and earbuds and after playing that first song, I knew straight away these were going to deliver.


Perfectly balanced EQ for the genres I listened to, rock, country and R&B. Hearing each cymbal hit, the bass drum punching through, riffs shredding and vocals are prominent. Putting something more poppy on, chart stuff like Jack Harlow, it again sounds fantastic and that bass, chefs kiss! While on the chart, Stick Season by Noah Kahan, a beautiful acoustic song and again, such a joy to listen to. I’m sure someone somewhere will pick up some very specific fault but for me, I think these are fairly faultless when it comes to performance.

That was the default, out-of-the-box performance but if you download the free app, it takes things up to another level. The personal sound is the first feature, which I’ve done before, it’s not a new thing by any means and it’s a test, where various different tones are played in both your left and right ears. If you hear said tone, you press yes, if you don’t, you press no and from this, a profile is created and it’s meant to be suited to your hearing. You can then go into the personal sound option and turn it on and off. I turned it on and off serval times, while music was listening and it was an obvious and positive difference between the default sound. Next, there are four EQ’s to choose from, Roomfeel is the first option which is PSB’s own sound profile. They’ve engineered this sound to deliver the warm, natural sound of a live performance. You’ve then also got Better Dialog, More Detailed and Tighter Bass. You can flick through them all and there are some subtle differences for me, I’d stick with personal sound and Roomfeel, which sounded the best in my opinion. The EQ’s look like they can be adjusted as you get shown the EQ sliders but you can’t, and you cannot create your own EQ either, yet. This feature may be added in the future. 


There are other settings in the app for volume and button controls, plus you can push firmware out to the headphones if available. 

Moving onto the active noise cancellation, it too is fantastic and it’s the obvious type. Sometimes I turn the ANC on headphones and it doesn’t sound like much has happened but with these and no music playing, you instantly hear the noise reduction and the outside goings on almost disappear. Working in an office with others chatting etc, will block that out. Walking outside in London, most of the hustle and bustle is gone. Given what I’ve experienced, I also reckon these will work well on a plane, which for me is usually where I want ANC the most, although I only go away once or twice a year and I’ve not been away to test these yet but if I do soon, I’ll drop a note in the comments of how they got on.

Other things worth mentioning, the microphone is good. I used these for a couple of teams calls and they sounded great, I followed up with a colleague and he said I sounded crystal clear so that’s good. Battery life is good enough, I’d get 20 hours easily out of them and I’ve charged them twice since opening them up. 

So final thoughts on the M4U9 headphones. They sound fantastic, some of the best I’ve heard in years. They’re very comfortable to wear, the ANC is equally fantastic, the controls work well and the battery life is more than enough for my commute and work sessions. The case is big and bulky, it does take up alot of space in my backpack but fine. Visually as well, not the best-looking headphones on the market, not the worst either and some may be put off by that but when you hear them, you really won’t care because you’ll be enjoying them too much. Price at £449, they are not cheap and maybe not that competitive, given these will be competing with the likes of Sonys XM5s which are about £140 cheaper, which is alot. 

For more info and to purchase, head over to the official PSB website.