Finished up my rack and PSU last night, looks great. The PSU is in a custom enclosure but otherwise all the regular stuff, parts from PTown and ClassicAPI, etc. I did a quick test last night and no audio passes at all through a known working module. Yikes. Troubleshooting tonight when I get home but the power supply checks out at the rack side, trimmed out exactly.
Edit: turned out that it was the patchbay I'd hooked it into. When I swapped out the old lunchbox I'd pulled the ends from the back of the patchbay without knowing it, easy fix. Everything works perfectly, I love this, thanks for a great project! Next up in 500 series is Igor's MixBuzz.