Sony WF

The Sony WF-1000XM4 have a smooth and warm sound profile. While they lack a thumpy low-bass, their mid-range is fairly well-balanced, so vocals and lead instruments are present and clear. However, their treble range is very underemphasized, so sibilants are especially dull and lispy. If you prefer a different sound, their companion app offers a graphic EQ and presets to help you adjust their sound to your liking. If you prefer a more neutral sound from your headphones, you can try these custom EQ settings. You can also find a comparison between this custom EQ setting and the headphones' default setting here. All the presets seem to dip at 7.5K in the treble range, and there doesn't seem to be a way around this, even when using a custom EQ. As a result, the default 'EQ OFF' setting results in the best treble response. Also, we did some subjective listening using a Samsung phone with an AAC codec, and you can clearly hear the underemphasized treble in songs.

These results are based on the headphones' performance with firmware version 1.1.5. You can see a comparison of their frequency response using version 1.1.5 versus 1.2.6 here. You can also see a comparison of their frequency response using firmware version 1.2.6 versus 1.3.3 for the left and right drivers separately. The original results are in red, while a blue line for the left driver and a green line for the right driver represents the new 1.3.3 results. However, the firmware updates didn't significantly change the headphones' sound performance.

Note: There's a slight discrepancy between the left and right drivers in the raw frequency response graphs due to how the files were processed. However, all other graphs are correct, and this difference won't be audible to most users.