The Analog Output Stereo Output module is somewhat based on the Barton Stereo Outs module. There are four AC coupled inputs with pan and level controls.
The headphone output section is based on the LM4808 datasheet circuit. This is an SMD (SOIC-8) part; all other components are through hole.
I’ve built this but my mechanical design was frankly stupid. I ended up kludging it together in a somewhat horrible way. I have eliminated the PCB design file and Gerbers from the Git repository; do better ones yourself! The circuit design is fine as far as I can see. So is the front panel except the slider mounting screws holes would be eliminated if I were to do it over.