Okay, so I loved the LCD-Xs so much (i.e., the best headphones I've ever heard, and I own a boatload, including most of the flagships) that I decided (yes, I know I am sick) to get the LCD-XCs for listening either in the bedroom or when there are people around (particularly wife shrieking and kids raising hell). So, placed the order with Headroom. Why so hasty only after a week of owning the LCD-Xs? I was afraid that they would run out of the black rim LCD-x, which are supposedly only available for a limited time (i.e., I find that the grey rim clashes with the black and wood finishes...don't like it one bit). I had the money right now, so I said, "what the heck". UPS says they should be in my office by Wednesday!
I have a pair of LCD-XC's, and IMO they don't isolate very well, unless the music listened to is loud, however isolation wasn't the reason I got the LCD-XC.
Also at the moment with the clamping, I find those LCD's are not comfortable.
If I want comfort and isolation though I just use my UM Miracles
The SQ I find from the LCD-XC, is very good apart from it sounding claustrophobic, which is to be expected with them being closed headphones, the headphones I also listen to are the 009's which IMO the LCD-XC can't touch when it comes to detail and transparency.