i believe the ath-m50 is the flagship (top of the line) model that they sell in a studio monitor headphone.
you are right, they do have a better low end then some other headphones i've compared.
they sound quite a bit more accurate than other phones i've had so i dont know what you mean by colored.
as far as loudness goes... i can crank it up on a phone or mp3 player to be painful....not sure how much more you want! its only 35ohm if i remember correctly. any higher resistance headphone may not work at all or give you even lesser volume without an amp. keep in mind getting a fiio portable amp might help in such cases (but is NOT required with the athm50)
@luccha
absolutely true. we can only give our opinions on products we have dealt with ourselves. what i may like may definitely differ from anyone else. checking it out yourself is always best but not always possible.
all i can say is that its the best pair of headphones that i've owned so far.... and that for the price i thought it was a good deal.