I'm using the Adafruit Metro M4 (Arduino compatible) microcontroller to build a MP3 player. I'm using the following components:
Adafruit Metro M4 feat. Microchip ATSAMD51
Adafruit VS1053 MP3/AAC/Ogg/MIDI/WAV Codec Breakout
SparkFun 16 Output I/O Expander Breakout - SX1509
I2C Encoder V2...