[vese]

What the hell is the difference? Im thinking about buying one of these used and I dont see what seperates them, obviously if the sound is the same on all of them then I'll go with the um2 rc but if the sound is difference I'll rethink my choice.

 

[Azathoth]

I found this thread to be very informative regarding the difference between the W2 and the UM2:
 
http://www.head-fi.org/t/576560/mini-review-westone-um2-vs-westone-2