Unbelievable Clarity, USE THE SAND CHAMBER!
So I've owned these for about a year now. Love them. But out of laziness I never filled up the sand chamber until a couple days ago. What a crazy difference it makes. It sounds like I have different monitors. Seriously. Actually it exposed how much of my low end was a facade. I have much less low end, which makes sense because I'm using Focal CMS65's which is still only 6.5" woofer. Everything just sounds so much clearer and present. No mud at all! One thing I feel like I can get away with is mixing at a slightly louder volume without it being completely inaccurate.
For the first time I feel like I've got a truly professional reference in my home studio. Quartet converters + MS100's w/Sand + Focal CMS65's + ARC 2. In love with mixing again.