Death by electric shock???
Does it happen when the Macbook is running on batteries - if so its possibly internal issue on the MacBooks USB port.
Does it happen when you are plugged directly into the Macbook without the hub ?
Does it happen on both K2 units ?
Do you still get a HF noise when you plug the K2 into the powered hub without connecting the laptop to the hub.
Grounding is normally LF not HF
Thanks for the replies.
First of all, the HF noise remains even while the macbook's power cable is disconnected. - Does this remove the grounding problem theories?
The USB hub is not powered.
I'll try connecting the K2s to the DB2 via XLink and use the DB2 as the soundcard. However this isn't really the ideal situation as it would require a DB2/4 wherever I play. The reason I bought the K2s was for portability and this obviously defeats the purpose. But I'll try it for troubleshooting's sake.