What we actually tested
Three weeks. Daily commutes, open plan offices, a couple of flights, and more back-to-back Teams calls than any human should have to sit through. Three testers, all with different use cases, all with opinions.
Sony had already won this category with the XM4. The XM5 had to justify its existence. Mostly, it does.
Noise cancellation
The best under £300. That's it. That's the review.
If you want more detail: it handles low-frequency noise brilliantly. Engines, air con, the guy on the train who thinks everyone wants to hear his conversation. All gone. Higher frequency sounds like voices are trickier, but that's true of every ANC headphone at this price. In a noisy office or on the tube, you will simply stop caring about the world.
Sound quality
Warm, detailed, not trying too hard. Bass is there without taking over. Mids are clear enough for podcasts and calls. Highs are present without making your ears tired after an hour.
The default EQ is a bit heavy for some people. The Sony app lets you adjust it, which is more than most rivals bother with.
It is a sealed, consumer headphone. If you are coming from studio monitors expecting a flat reference sound, you will be disappointed. If you are coming from whatever free earbuds came with your last phone, you will think these are witchcraft.
Comfort and build
Here is the thing Sony got wrong. The XM4 folded flat. The XM5 does not. It fits in the case, but the case is now bigger. For anyone who travels light, that matters.
Aside from that, the headband is comfortable, the ear cups are generous, and after four or five hours you get a bit of warmth around your ears. Sealed headphones run warm. You knew this.
Battery life
Sony says 30 hours with ANC on. We got between 28 and 31 depending on volume. For context, that is Monday to Friday without touching a charger. Ten minutes of charging gets you five hours back. Genuinely useful.
Should you buy them
If noise cancellation is the main thing you care about, yes. Nothing at this price does it better.
If you already own the XM4 and it is not broken, save your money.
If you are choosing between these and the AirPods Pro 2, it comes down to ecosystem. Android users, get the Sony. iPhone users who are already in Apple's world, the AirPods Pro are harder to argue against. We reviewed those separately.