I want to try to play wav forms that sound decent (and could easily be edited by anyone, so adding a wav file or something) over a good speaker (non-piezo). I am thinking of using an SD card to read off of because I've seen posts on it before. Was curious what route you would suggest to do this, I want it to be completely standalone from computer.
Have you seen the adafruit wave shield?
For any decent quality you need an external D/A converter in your setup as well as a some sort of permanent storage.