In a test conducted by a German magazine (via BGR), they actually found that audio output using the 3.5mm adapter is actually worse than if you were to plug in directly to the 3.5mm jack itself. Part of the article reads, “The results are clear: with an iPhone 6S, the dynamic range worsens by 4.5 dB(A) for 24-bit music files. For the iPad Air, it worsens by 3.8 dB(A). The signal also gets worse for 16-bit music files, even if they aren’t that drastic: the dynamic range worsens by 1.8 dB(A) and 3.1 dB(A) for the iPhone and iPad, respectively.”
Now before you start packing up your iPhone 7 or 7 Plus to return them, we should point out that this is only on paper that it sounds worse. In theory unless you have an exceptionally keen sense of hearing, we doubt that you would be able to tell the difference as well, although now that you know this maybe mentally you’re already thinking that it sounds worse.
Not to mention the audio source also matters, meaning that if the music files you’re listening to are regular compressed MP3s, then you probably won’t be able to tell the difference, but what do you guys think? Can you tell there’s a difference in audio quality when using the adapter?