(Read about our ratings)
Rarely in my reviewing career have I come across a product I wanted to like so much, and in the end, couldn’t actually recommend. I love the sound of the M4U 9 headphones. On that undeniably important aspect, they’re fantastic. They’ve got a well-balanced sound with a bit of extra bass, and that’s exactly the personality I like in a pair of headphones.
The problem is, they creak. A lot. If you move your head, the hinges on the earcups make a clicking/creaking sound that’s exacerbated by how microphonic the frame is. It’d be bad for a cheap pair of headphones. At $499 (all prices in USD), the M4U 9s are decidedly not cheap.
This is going to be a rather atypical review, but I think you understand why.
In the box
There’s a lot of stuff in the box. You get a football-size carrying case, a 3.5mm-to-3.5mm analog cable, a USB-C-to-USB-A charging cable, a 3.5mm-to-6.35mm (¼″) adapter, and a dual-mono adapter for use on some aircraft.
These headphones are extremely microphonic. What that means is they seem to amplify any physical contact or mechanical motion into extremely noticeable sound. To an extent, all headphones and earphones can do this. What varies is how audible it is. In the case of these PSB headphones, it’s loud. If this were just something that happens when you touch the ’phones, that’d be one thing. Not great, but how often do you actually touch your headphones when listening? Unfortunately, it goes beyond that. The earcups are on a hinge that clicks or creaks when it moves. If you sit perfectly still, you’re fine. If you turn your head, tilt your head, or even move your jaw, you’ll hear it. It’s louder than music at a normal listening volume. To make sure it wasn’t my vast, empty noggin making the noise, I gave my sample to some friends. They heard the same sounds.
It’d be fair to wonder whether I just got a bad review sample. Unfortunately, that doesn’t seem to be the case. I received my first sample of the M4U 9s in November. Discovering this issue, I reached out to PSB. They replaced my sample at the end of December. The new ones had the same problem. A fellow headphone reviewer also had problems with their sample. As of this writing, there’s one review on Amazon, and that person mentioned this same issue.
What makes this heartbreaking is how good the M4U 9s’ sound quality is. If they didn’t sound good, the build issues wouldn’t matter because they wouldn’t be worth considering. However, they have a warm yet detailed sound that’s pretty much exactly what I want to hear in a pair of headphones.
With the title track of Crossing Muddy Waters by I’m With Her (24-bit/88.2kHz FLAC, I’m With Her / Qobuz), each strum of the guitar rang cleanly, blending perfectly with the harmonized vocals. The synth drop at the beginning of “Everything in Its Right Place” from Radiohead’s Kid A (16/44.1 FLAC, Capitol Records / Qobuz) sounded wonderfully huge. The various hard-panned sounds in this track seemed to sit well over my shoulders. The bass was full without being overwhelming.
I’m not sure they sound $500 good, but I like their sound more than that of the various $300 noise-canceling over-ear headphones I’ve tested recently. This review would have been so much easier if they sounded bad or even just average. So it goes.
If these headphones cost less than $100, this level of noise from the frame would be annoying, but if their sound was great, it might be an acceptable tradeoff. For $500, though, that’s a very hard sell. There are a lot of great-sounding headphones for that money or a lot less. That Amazon review thought the M4U 9s’ sound was good enough to offset the frame noise. I can’t be so forgiving—not for $500.
I have little doubt that PSB will release an “M4U 9 MkII” or “M4U 10” that addresses this issue. I look forward to hearing them. Until then, skip the M4U 9s.
. . . Geoffrey Morrison
- Smartphone: Google Pixel 7
PSB M4U 9 Headphones
Warranty: Two years, replacement.
633 Granite Court
Pickering, Ontario L1W 3K1
Phone: (905) 831-6555