[Fungus]

Would the pro 40 and 50 improve on the um3x sound signature or sound totally different. 
I'm looking for an pair of iem that will retain the forward mids and instrument separation of the um3x but improve on the treble detail.  

 

[Smurfs2010]

Not sure if you have read this thread but it might help you - http://www.head-fi.org/t/677181/westone-um-pro-series-thread/690
 
I love my Umpro30 but can't comment on your question.

 

[lancer7777]

um3x won't let you down