It's subtle - not undeniable.
If it was a comparison with a $15 headphone, it would be undeniable.
I agree on the bass; it is more textured, but the clarity overall between the two is very similar.
The rolled off treble on the Momentum doesn't mean it has less clarity than the more trebly M500. They're both excellent at detail retrieval.
I don't think it's subtle. I think DACs provide subtle sound differences, I think the difference with burn-in is subtle but the difference in overall clarity between these two headphones is clearly noticeable without much extensive listening. But, as we all know, all is relative.
I do think the Momentum fares very well in terms of clarity too, though. I really like the Momentum and before I heard the KEF the Momentum was my king of the hill as far as portables go.
Edited by Lan647 - 9/27/13 at 2:34pm