I no longer have my Mojo2, but I do have a Hugo2. Hugo2 sounds very similar to Mojo2, albeit a little more controlled over all and some say, a bit brighter. Power output and impedances are pretty similar.
LCD-X and LCD-XC are both very efficient headphones, requiring little power to go very loud. Indeed I do believe they use the same drivers, just one happens to be a closed back, and that causes a different tuning (frequency response).
When I first heard the XC's at a Canjam with my own Hugo2, I was so smitten with the punch and attack and ofcourse the clarity of the sound (compared to my then, a modded Hifiman EDXS) that I bought one a couple of months later! A violinist friend, heard mine and loved it in an instant, but he wanted open back, so he got the LCD-X.
I have heard both headphones now with the Hugo2, and I can assure you, there is no sluggishness or slowness to the sound, what so ever!
What I suspect is, that some amps may create a distortion that in turn is heard as a hardness to the sound. Since the Audeze's have the lowest distortion ratings of many, that distortion, becomes very audible, and then it is mistaken as Attack.
Mojo2 can drive the Audeze's perfectly, to very loud levels. Scientifically and Subjectively.
Do not dismiss objective/scientific reasoning behind these arguments just because you are on a Hifi forum. People like Rob Watts and other top designers, design the very gear we all use, purely on scientific reasoning and objective measurements. They do use subjective listening testings AFTER they have nailed the science first.
The book confirms that Mojo2 and LCD-X (and indeed XC) will have no issues, and I confirm that they don't.
