RobR, I have a HCA1000 ($300 used from a stereo repair guy) and it is sensitive to ground loops which cause a hum. I removed the ground pin from the power plug and it's fine. I really should get a power conditioner but would rather put the $$$ elsewhere in the system for now. My old Carver amps were just 2 prong so I figure it should be OK. Good Luck in your search.