The DJ100 is closer to the KSC75 sound compared to the Porta Pro since it has a titanium driver also.
You can demo the DJ200 (should be the same as the DJ100) at any Best Buy in the pro audio department.
That's what I would suggest.
The Porta Pro, UR-55 or KSC75 might be better for portable use unless you can use your Fiio E6.
The Porta Pro (based on memory) has less treble and more of a mid-bass hump. Probably worse low-bass extension but I'm not sure about that.
It really depends on preferences. The DJ100 should be more neutral than the Porta Pro.
Edited by tdockweiler - 4/7/13 at 6:12pm