[subseasniper]

Quick question here.
 
Are the 598's the same as the 595's on the inside but with a new paint job or are they different cans entirely?

 

[s0ckpupp3t]

As I understand it, different drivers and driver enclosures between the HD595s and HD598s.  I have the HD598s but have not compared them against the previous generation.  
 
There are a series of articles on Headphonia reviewing the HD598s and comparing them against the HD595s, HD558s, HD600s, etc.
 
http://www.headfonia.com/sennheisers-new-hd558-and-hd598/
http://www.headfonia.com/old-and-new-hd555-hd558-hd598/
http://www.headfonia.com/hd600-and-hd598-comparison/
 
 
The consensus seems to be that the HD598s are an improvement over the HD595s but whether its worth the cost of upgrading, I don't know.