How to play mp3?

Question

Audio

There is a good Sony str-de405 receiver with good speakers, you need to connect some device to it that can play mp3 and must have a headphone output to transmit the audio signal to the receiver. There is an adapter from bells (receiver) to mini-jack 3.5 (player).
The question is what is better to connect? the mp3 player needs to be charged regularly (an extra problem), the laptop cannot be used there.
A public place, open (free) music will be played, a person should turn it on as simply as possible and not know the problems.
Thanks in advance for your advice, I've been scratching my head all day.

Answer 1

Why charge an mp3 player? Plug it into a power outlet and it will charge itself when needed.
Or what phone...