thanks for the quick response! I'd prefer a closed set of headphones, as I like the noise isolation and don't really want sound leakage. I don't currently own an amp, but am not against getting one.
For sound signature, I'd prefer something that's more neutral than the M50s, with a little more (but not much more) emphasis on the mids. I don't normally turn my M50s up that high, anyway, so I don't quite get to the point where the mids are notably recessed.
I'm looking for headphones to use for commuting and work, I have my Samsung SGII for a music player and just my PC at home/work. As I've said, I don't have an amp yet, but am not against getting one.
As for other headphones, I quickly tried most of the demos at a local Best Buy, but didn't really pay attention to comfort at the time.
The Sony ZX700. More mids-emphasis and tonally overall suited to soft music. An Fiio amp will bring out the low end punch for hiphop/rock. It's also over the ear, portable, closed back, comfortable and has good noise cancellation.