Pros: 1. Extremely coherent and linear sounding all across the frequency range
2. Beautiful midrange with slightly warm tilt
3. Powerful, rumbly, quality bass
4. Zero fatigue, extremely smooth sounding. Perfect for long listening sessions
5. App and features are pretty useful. Probably the best out there
6. Great ANC performance
7. Batshit crazy battery life
8. LDAC supported
9. Responsive to EQ
10. NATURAL SOUND
Cons: 1. Stock tips are trash
2. Touch control is a bit too sensitive but not a dealbreaker
3. Can be uncomfortable with the stock tips. extremely comfy with final E type and SONY hybrids though
WF 1000XM4 is the latest TWS iteration from SONY following the success of XM3. While I am not a fan of the over ear version (WH moniker), SONY has knocked it out of the park with the TWS. Its not underrated by any mean. Sony products are popular as ever despite their weird naming schemes but their wireless stuff might not be taken seriously by audiophiles. Well, XM4 kicks ass and it deserves every bit of attention from audiophiles as well.
I will be talking about only the sound as tech stuff and battery life of XM4 is pretty much the best out there so not an issue. Another big thing to note is the stock tips.
Sony, being the weirdos, has decided to bundle in some foamies that'll ruin the sound and irritate the heck out of your skin. Throw those away, put on some aftermarket silicone tips and you are in for a treat.
XM4 has an overall warmer presentation but its not v shaped per se. Mids don't sound recessed and they are prominent in the music. Vocals sound exceptionally good and rivals/outperforms wired IEMs in the similar price range. Bass is actually pretty well done. Its a consumer focused product after all. SONY has opted for an elevated but precise bass presentation here which I really like. There is very little to no bleed in the lower midrange, keeping everything nice and clean. Treble response, while being smoothened out and polite is not muted or dark at all. It can be sparkly and airy when the track calls for it and you can always EQ the treble. TLDR: Exceptional tonal balance and coherence, a direct trickled down tonal successor SONY's absolutely awesome IER lineup of IEMs . Once of the best timbres you can find in an IEM under 500 USD
As for technical performance, XM4 performs far better than expected. Very precise imaging and good soundstage. Detail retrieval is also commendable especially with LDAC on. Sony's previous mode, XM3, had a prototype feel to it. XM4 is a far advanced and competent model. Totally worth the price and highly recommended
Sony Hybrid Silicones (stock tips of IER m9/m7) and Final E type black both are great. They sound 70 percent like the awesome M9 with these tips. I vastly prefer XM4 to wired chifi iems under 500. These are that well tuned.