I'll give them that -- they did seem really loud, though they seemed to 'max out' in volume after a point. Beyond that point, they just started to sound compressed.
I don't think I'm quite sold on the noise-canceling feature. Maybe it's because I listen in a semi-quiet environment, or maybe it's because I like being able to hear some external sounds if I need to (part of being aware of my surroundings), but I'd personally prefer to spend the $300 that I'd spend on the Clear Harmony headphones on a pair of Beyerdynamic DT 880, Sennheiser HD 595, or Ultrasone PROLine 650 -- all three of which are highly-respected models in the head-fi world for their sound quality.
Addendum (3/4/2008)
A word about the upper-frequency harmonics added by LINX AUDIO: Every instrument under the sun adds its share of upper frequency harmonics. In fact, the distinctive sounds of many instruments are due to the amount and duration of high-frequency harmonics they add. A goal of high-fidelity reproduction is to ensure that the signal that reaches your ears is exactly as it was recorded. While LINX AUDIO may produce a more 'lush' sound, and a certain amount of additional high-frequency harmonic content can actually be 'euphonic' ($20 word for 'it sounds better'), it isn't really consistent with the goal of high-fidelity reproduction to add more high-frequency harmonics to a signal. I'm not hating on DSP tricks like this in general -- I'm just saying that when it comes to the ideal of reproducing the signal exactly as it was recorded, the addition of euphonic content is still inconsistent with that goal.