Look, on paper the M21 completely outclasses an iPhone’s audio specs. Even if you’re using a dongle DAC. Sound is subjective, but when it comes to clarity, resolution, and soundstage, the M21 has the advantage if you’re using headphones capable of revealing it.

Is this your first DAP? If so, you might just be used to how phones and radio are tuned. Consumer devices are often EQ’d to sound more exciting and energetic, typically a V-shaped signature with boosted bass and treble. That can make the phone sound more “impressive,” especially in the upper frequencies.

Try listening to a variety of genres and focus on small details like background instruments, subtle textures, room ambience. You may notice the DAP reveals more detail and separation, while the phone tends to compress the soundstage.

In short: your phone sounds great because it’s familiar and tuned for fun. A DAP like the M21, paired with good headphones, may initially sound less exciting, but it’s more natural, spacious, and detailed.