Last week we put the EY HWS on it's own separate power supply to see if this would reduce the 57Hz coupling of the HWS into DARM.  This workes. When the EY HWS is on, we see no coupling into DARM at 57Hz. (See attached sprectum.)  EX is still on the shared power supply, and the 57Hz line is clearly present.  The current setup at EY is only as temporary setup.  It looks like we should permanantly move all the HWS onto their own power supplies.