Beyerdynamic Custom One Pro

This is a popular headphone and for good reason.  It's VERSATILE!  It sounds great out of the box, but it's no fun to leave well enough alone.  This is DIY modification.  The midrange is among the best I've heard.  No annoying resonances, plenty of deep bass, excellent isolation, etc...  For recording, these are hard to beat.  Close the slider for your vocal performance, put it in 2 or 3 for a nice, neutral performance, and open'er up to see what it will sound like in a teenager's car.  It grips your head and lets you know it's there, but it's not overly abusive.

Here's what Beyerdynamic gave me after adding their velvet pads originally made for the DT770.

The third or fourth position give the smoothest performance, but not the flattest.  Hoping for tighter(faster) sounding bass, I chose to EQ the third position.  Decreasing the work your amp has to do never sounds like a bad idea to me.  So I got to electronically reduce the bass and let the physics of the alignment do the work.  Here's how it turned out for my subjectively flat setting updated 05/08/13:

This one requires more filters than my previous attempts, but the sound is worth the effort even if it's not perfect yet.

1st filter:    60Hz       -12dB    Bandwidth: 2.54

2nd filter:   141Hz        5dB    Bandwidth: 0.48

3rd filter:    250Hz        6dB    Bandwidth: 1.39

4th filter:  1000Hz        2dB    Bandwidth: 1.39

5th filter:   1340Hz      -2dB    Bandwidth: 0.43

6th filter:   2300Hz      -3dB    Bandwidth: 0.64

7th filter:   8400Hz      -9dB    Bandwidth: 0.71