u can get in mediaplex in mid valley or klcc, or can direct contact the senn distro as stated in 1 of the pinned thread.
i haven tested the mx550, but my friend complaint that the bass of pmx60 isnt as
good as sony MDR-G74SL streetstyle headphone.

px100 might b a better choice among the 3. its priced at rm199 at mediaplex, but direct contact the distro might fetch rm140 include of postage (if i m not wrong). however, its quite loose and cant clamp at my ear,tat's y i don like it.

just my 0.2 baht 

check out my reply to your previous question on the last page
among those 5 i'd still take the PX100

but i think you might wanna decide whether u want headphones or earphones first
if you're gonna be carrying it in your pocket together with your player, i wouldnt take any of the headphones 

if you're wearing spectacles, forget the kcs-55
i broke mine out of frustration cause they were so damn uncomfortable