An MP3 player?
You mean a smartphone?
Models range from around$1to more than$3,000and they vary at least as widely in feature sets.

Listening to music around the clock will consume your smartphone’s battery and storage.
Likewise, a large FLAC library could fill most smartphones and not every handset has expandable storage.
Enough said if you value tactile controls.
Buttons are easier to operate without looking while running/biking/driving etc.
Some additional considerations we had while shopping for an MP3 player… Fortunately, this specification is easily found in models under $50.
Although the X02/A02 largely met our desired specs, this model doesn’t have independent volume controls.
Build quality:Lighter than we thought.
Easy to orientate in your pocket.
Buttons feel like they should wear well over time, as do the headphone and charging ports.
you’ve got the option to also insert a microSD card up to 128GB.
Screen quality:Pixelated compared to a smartphone.
The screen resolution combined with the software interface feel reminiscent of an old feature phone.
User interface:Some of the X18’s interface features…
The rig input mostly functions as expected despite some quirks.
For instance, we couldn’t find any way to search for files.
Among thewaterproof modelsavailable, “Audioflood” sells a modified iPod Shuffle with waterproof earbuds.
Here are otherRockbox portsin development.
Entry-level “hi-fi” and up -These models/brands were beyond our interest and ability to make a recommendation.
Image credit:Some MP3 playerphotographycourtesy of Shutterstock