I also have a pair of ATH-m20, an older version of these headphones and a lower cost. they do not have the detachable cable, but the reason I'm sticking my head in here again is because of the sweat issue. I sweat a lot! My sweat destroyed the ear pads on the ATH-m20's and I ordered some replacements for $5 on amazon.

voila'! refurbished headphones! and IIRC, the ear pads are the same on the 40's and the 50's as they are on the 20's (and maybe the 70's and above, too, I'm not sure).