Misc small fixes which came up when trying to order from JLC PCB with PCB Assembly:
Fix JLC PCB component orientation
Add do-not-populate to all THD components
Fix JLC part selection, tweak values to be standard components
Explicitly select some capacitors
Explicitly select some resistors
Tweak resistor values/ footprints to be standard instead of extended parts
Breaking changes:
Moved potentiometers of channel mixer 3 mm down (closer to board edge because the mono pots don't need as much space as the stereo ones used previously)
Misc small fixes which came up when trying to order from JLC PCB with PCB Assembly:
Breaking changes: