My partner in crime, Andrew Beer, has come up with a slight modification to the Amp board to improve the audio output quality. It does nothing to improve how the computer "hears" the files but it is a lot nicer to the human ears.
It's nice and simple. Just remove the Capacitor C1 off the board. (Circled in the picture)
Plea To Arduino Programmers.
O.k. I have to admit defeat here with improving the programming. I need help from anyone who can either add or tell me how to add LFN support and maybe a basic loading animation and possibly even some sort of display of a countdown as to what's left to play of a file. Later on I will also need your help to see in onboard conversion to wav is possible. Big ask I know but it would be nice to get the project moving forward again.