I have sample sketches working separately with the mp3 module and the rotary encoder. The next step is to get them working with some sort of visual indicator. I think I have enough analog IO to push a 7 segment display.
Where do you find a panel mount xlr connector, a 1:1 audio transformer and a project box for $8? In a pyle di from amazon.com!
I was going to leave the transformer on the pcb but I need to relocate it to accommodate all the other bits…..
http://www.amazingtips247.co.uk/2015/11/how-to-play-sound-tracks-with-catalex.html
http://bildr.org/2012/08/rotary-encoder-arduino/