emulatorII-list

It's a grounding issue. Check that all your earth connections are secure and are not 
corroded. It might also help to replace the SCSI cable on the HD, and ensure that it is 
not very close to the audio output stage. Also try using DI boxes to isolate the EII- 
place them as close the the samplers outputs as you can.

If none if those things work, a decent tech should be able to do a more thorough 
check of the grouding throughout the unit.