Maybe I should start buying cables from Jesus?

With modern equalizers you would have to be nuts to actually perceive an unwanted distortion.  I do not even know if there is recording hardware that can capture the distortions produced.

  When your kilo-buck system has biceps like these  

Yes, have you used Winamp pre2001?  Older computer hardware had limitations, especially the lower end stuff. A firmware I flashed to my Nexus 4 had something wonky with the DSP, so EQ was causing nasty hiss.   Not really much from the top of my head, but my hesitance towards EQ came from...

UE6000 is over ear? Think I might be getting confused between the UE6000 and UE4000 You are right about the DSS.. Thought the back jack was for mixing a mic, just another input. A shame since the Mixamp costs quite a bit more

I have been considering the ZMF as well. Hopefully someone can chime in, coming from the A900x/K550 and hoping for a worthy upgrade!

I have the M5, they are not neutral, but certainly not 'basshead' imo

I wish Sony had a new Smartphone+Walkman refresh.  Hate carrying around a large phone and dap. Not sure if the X5 reviews are hype, but I am considering upgrading my WMZ-Z1040.  Excellent player, but has very little storage

Earforce DSS would get you surround cheap (paid $17 used online), definitely works with PS3! M100 is also a good headphone, but it is likely over your budget. Not sure of any other 'trendy' headphones that sound good, and are full sized haha

Reviews make the X5 look significantly superior, but I personally have no idea. 

Severity depends on the software and the hardware used.

I recabled my stock DT880s with some tapped alumium foil.  Smoother treble, midrange is a tad forward, much better than stock!

A USB-DAC + Razer surround software might be something to consider. Works well once setup, and imo USB DACs are better value money wise.

+1 on the X3!