I had the Audeze LCD-X (and LCD-XC) at the same time that I had the Ether C -- and ended up selling the Audezes. Heaviness and comfort aside, I found the Audeze LCD-X ultimately to have too much bass emphasis and not enough resolution (though resolution was still very good.) Yes, the bass was delicious at times, along with the fullness and weight imparted to music, but it was too much of a good thing, imo. When I switched to the Ether C, the additional detail was readily discernible - the old cliche "I heard things I never heard before" applies. The Ether C was truer to the music and much faster - the LCD-X was lusher and slower. Also, while less in absolute amount, the bass on the Ether C was faster and tighter and also may go deeper into the sub bass category. It was a clear cut decision imo, and several others on Head-Fi have posted similar comments in choosing the Ether C.
However, note that in April, 2016, Audeze modified its entire headphone line (except for the new Sine) and stated they changed the drivers and made some other changes. I don't know what the new ones sound like -- my comments above relate to the "old" Audeze versions from 2015.
