humming from definitive technology sub

[MobiusStrip]

I wouldn't think it's a grounding problem if the sub isn't hooked up to anything else. Ground loops typically occur between pieces of equipment.

I have the same problem with a Definitive sub: loud hum with nothing hooked up, and my power filter indicates a good ground on the outlet.

The guys at Definitive were quite responsive and even looked at the amp free, but said it wasn't humming for them. But I've hooked up another speaker to the amp and the hum is there, regardless of where I plug it in.

At this point I guess I just have to junk it.