To reproduce good quality sound you need a digital to analog convertor chip (DAC). This chip can be connected to the spark SPIbus for instance.
The new Photon is equipped with a 1 channel DAC, but for audio quality applications I doubt if it is good enough. Most on chip DAC’s are noisy. There is of course a lot going on inside a chip .
So my advice would be, check if you can find an audio shield for an Arduino, patch it to the Core and write an awesome library that read audio data from an SD card, @kennethlimcp made a good SD card shield.
It won’t be easy, but if you succeed and share your project you will make a lot of new friends!