Continuing from my earlier posts about ongoing power issues in my studio causing my equipment to glitch out, specifically the SPDIF link dropping sync whenever a nearby lightswitch is toggled.
Turns out that practically every lightswitch causes an RF burst when toggled. One of the pieces of equipment (E-MU 0404 USB or Yamaha M08) is incredibly sensitive to this field, and will cause "jitter" or signal loss between the two units.
I know the problem is "in the air" because I've run the two units off a battery UPS and *still* have the glitch - it's not the connected wiring after all.
It appears that many manufacturers employ a ferrite bead to deflect the RF interference, although the Yamaha power supply clearly lacks this feature...not sure why.