The 6 Moons review didnt sound too positive to me. One reviewer ( below) saw no merit to it the other (below at bottom) thought it maybe made a improvement.
First Reviewer
"After 'breaking them in' for the equivalent of 40 hours or so, I experimented with the devices in three systems in three different venues; with three different speakers, two different preamps, two different amps, one integrated, one receiver and one CD player. Over a series of sighted A/B listening sessions, I sometimes reckoned that I heard a touch more body and low-level dynamics in the mids. But the differences werent tenacious enough to trust. In unsightednot double-blindA/Bs it became clear that I could not dependably identify when they were in or out. The same held true over periods of long-term listening. Since I was unable to reliably detect the possible differences in or out of the various contexts explored, I have to say that the Ground Control devices arent for me. Your mileage may vary."
Second Reviwer
"I will go so far as predicting that some audiophiles might not hear any improvements either due to their systems not revealing them or their lack of sensitivity to the particular sonic benefits the GC devices convey."