Hi Arthur
What's confusing me is that you, ChrisPa and others are 'reporting' improvements in SQ when using a USB Isolator even when there is no 'problem' to fix.
You say 'The isolator is there to break the electrical connection between the USB and DAC' but according to Device Manager (WinXPsp2) the USB Hub I'm using exclusively for my M-DAC shows Power Required 0mA.
So, if no current is flowing, why would an Isolator be needed to break the electrical connection and how would this improve SQ?
Maybe worth checking your Device Manager (or equivalent) to see for yourself.