Hifiguides Amazon Link
XM4 Link: https://www.amazon.com/dp/B0863TXGM3?ref=dacx_dp_5094693960501_3808467060901&me=ATVPDKIKX0DER&pd_rd_plhdr=t&aaxitk=3oRuf-xf5ZAAQFUJKozGvg
Introduction
This review will focus on the XM3 model of Sonyās flagship BT+ANC line of headphones. This headphone is reviewed to death all over YouTube and the internet at large. So, I wonāt go into details about build (pretty good), comfort (also very good, maybe the earcups will get too warm for some), the quality of noise cancellation (itās really awesome), battery life (it is pretty much what Sony claims it is), mic quality (it does kinda suck) etc. This will be a sound review. Here goesā¦
Sound
Signature:
Iāll focus on the stock signature. The included app has an equalizer so this headphone can be tuned to just about any signature you want. The stock signature and tuning of the XM3 are āmainstream.ā This is neither good nor bad. It translates to a very bassy presentation with a slightly recessed midrange and treble level that is between the mid-range and bass. If anything, they tend toward dark, but are not devoid of sparkle. The intent was clearly to find a tuning that was not going to be fatiguing for most people over long listening sessions. Sony probably succeeded here. On the occasions Iāve worn them for multiple hours I did not find their sound fatiguing. Some listeners may find the bass fatiguing. The bass is deep and extended. It has pretty good pitch and definition and speed that is best for genres like pop and hip-hop. Itās not as good for rock and metal but nor do I find it overly objectionable for those genres either. The treble is present and at times has sparkle. Sibilance is rare, even it very brightly recorded or sibilant tracks. Thereās not a lot of air either; the treble extension isnāt great. The mids are not a focus. They are there and are adequate. At the same time voices sound enough like voices, pianos enough like pianos, guitars enough like guitars, etc. to not be distracting. The overall signature thus is enough to be pleasing but is not going to bring out every nuance of the music.
Detail Retrieval:
The XM3 is relaxed and is not a detail monster. For what this headphone is as a Bluetooth and ANC can, thatās fine. Itās detailed enough that if you listen closely youāll still here that 128kbps mp3 files suck, but itās not going to consistently differentiate between a 320kbps file and a lossless file. Is this because theyāre Bluetooth? Is this because theyāre active noise-cancelling? Or is this a deliberate tuning choice for long listening situations? My guess is āyesā. Still, the amount of detail is enough that itās not distracting if youāre involved in some task.
Spatial Performance:
The soundstage is not wide but nor would I call it claustrophobic. There is still an āin-your-headā effect to the sound. Imaging is a bit ā3-blobā-y with L, C, and R. There is sonic info in between but not a lot of instrument separation. This probably comes back to the detail retrieval just discussed.
Other Notes:
These headphones can be plugged in and run wired. If they are not powered on during this they sound laughably bad. There is clearly lots of DSP going on here to get them to their āstockā signature. I did get modest improvement in sound quality by powering them on and them feeding them signal from a higher quality dac. That provides some evidence that the Bluetooth transmission still has work to do on its quality, but this difference was not very large and I had to listen closely to pick it out.
Final Thoughts
Iāve had these XM3s since about February 2019, I believe. Iāve used them on airplanes, while mowing the lawn, and while moving about doing housework and such. They work great in such settings. They have a place in my collection for those reasons. Yes, for their price you will find better sounding headphones to give an audiophile experience. However, I rarely use these headphones when the sound is the focus. I use them when the activity Iām doing is tedious and requires movement and the music helps make it less tedious. These cans do a great job of that. They also fold up nicely in their included carrying case and take relatively little room in a backpack or suitcase, making them great travel companions. If you want wireless and ANC, and sound quality thatās at least good enough to get out of the way while you focus on some other task, these are an excellent option.
Iām listening to my gfās wh-1000xm3 now. For me, these have very limited reason to exist tbh. The ANC is nice and all, but Iāve never been in a situation where IEMs with a good fit donāt keep out the sound enough.
The soundstage is smaller than Iāve heard on IEMs and there is something unnatural to sounds, I feel like the timbre is off. It doesnāt help that I donāt like recessed mids I guess.
I also happen to find these way more uncomfortable than my own headphones (he400i 2020, dt-880 and mh752) which is perhaps the biggest surprise for me since expected these to be very comfortable.
Iām finding the XM4ās clipping on plane takeoff, whichā¦ I donāt remember happening with my Bose QC35ās? Theyāre fine most all other times, but during liftoff and landing I was getting a bunch of clicks and pops. I remember the Bose having more of an airy feeling to the sound. Sorry I canāt really A/B, I got the XM4 because Iāve misplaced my QC35.
Between the two Iād keep the Bose. When I find them.
Thatās super weird, my M3s donāt have any issue. Have you tried a firmware update/flash? The companion app should let you check that.
If itās only happening at takeoff and landing, I wonder if it might have anything to do with rapid changes in cabin pressure. Thatād be my guess more so than anything firmware related. If they designed the chamber without adequate venting, the pressure changes could potentially impact the range of motion of the driver.
Yes, they were fully updated at the time, app installed, I ran the cancelling optimizer before they turned on the engines, and then at cruising just for the heck of it.
The only thing I havenāt done is send them ear pictures, because, nah.
Cabin pressure changes might maybe be something, butā¦ cabin pressures were fairly stable. When I re-optimized during one flight we were at 0.9atm according to the app, 1.0 on the other.
I dunno why that would be an issue on the XM4 but not the 3 
, I clocked ton of flights on mine and never had an issue.
Maybe itās just DOA?