I've just set up mine a few minutes ago and I'm instantly blown away by how they sound... at first they felt a bit like a downgrade from my Alesis Monitor One MkII simply because they're like half the size but immediately after trying them out on a mix I did last week, I was very happy with my purchase.
The oscillating hiss is there, however... I've tried different power cables with no result... I guess I'll wait a few days to see how annoying I find it and then make a decision.
It would be a shame to let them go, though...