These really aren't anything like Sennheisers in terms of construction so I don't know that experience with that sound will help much to describe these cans. I just tried them vs. some ATH-AD900s that I like a lot and found that I prefer the quicker, punchier sound of the new cans. The ATHs easily win on comfort though. Those who want a really tubey, big tone midrange kind of sound may not like these new cans that much. These are more of an extended frequency sound without much mid bloom. Clean highs, more of a neutral (maybe less intimate is a reasonable descriptor?) mid sound, and very dynamic bass that actually lets your ears feel some impact. Not like gut pounding bass, but there is a definite tactile element that I found a nice surprise. Vocals sound balanced and resolved, but they don't do "big head" or "chick whispering in your ear". Maybe the best description is that the cans seem to bring out those OTL amp positive attributes of tight bass and a very clean sort of sound.
One thing for sure, I could REALLY hear the improvement that John Swenson's software filter makes over the DAC chip's stock filter. Turned out I had been running the stock filter all day during a listening session on Friday - arggh.
