I've got the pk1, Sony E888 and the M2C. I also spent some time with the pk2.
My M2c aren't fully burned in I guess, but they have at least 50 hours.
M2C's are crisp, clear wid and spacious. Detail, clarity - it's fabolous. BUT: They have little bass impact, and to me they are fatiguing. Don't worry about that too much - I'm a very picky person with regards to fatigue. But they are on the bright side.
When properly amped I really love the pk1 - they're my definitive top pick. They are really great, especially with tubes.
From an iPod I prefer the E888 to the M2c due to warmth/less fatigue. Amped, I seem to prefer to M2C.
For detail and soundstage - the M2C rules. I find them not "warm", very much not "bassy" but very very "clear" - to answer your question directly
My mileage is from desktop amps (SS and tubes) and a iPod classic.