How do you propose that you'd select and load tracks? Or view time remaining. Even if you don't care about a waveform display, some sort of computer (ie. display) seems to become necessary at some point. Perhaps you could check the PiDeck project, which puts xwax into smaller hardware.
A friend of mine was doing Technics repair and customization and about 6 years back we started building a prototype of embedding a Pi with a 3.5" LCD in the body of a 1200. I build a custom Qt GUI for xwax that was controlled by a single rotary encoder with a push button. We could throw out a lot of the UI since it was only ever playing one track at a time. He eventually got called up to be Alle Farben's touring sound guy and we never picked it back up once he was back.
