Corda Soul
More info on this unique device here.
Audeze LCD-2 Headphones
These planar magnetic "ortho" headphones have wide, linear frequency response, neutral tonality, and phenomenally low distortion. I've already described them elsewhere.
Behringer DEQ2496
This performs DSP in hardware. I use it for parametric EQ for headphones & speakers. Details on EQ settings here.
GENERAL OBSERVATIONS
Overall this has some of the lowest noise and distortion currently available in any headphone system. It is as close as you can get to the sound of the live mic feed, or to an actual live performance of acoustic music. The sound overall is similar to my in-room system with its Magneplanar 3.6/R speakers. The differences are the in-room system is a hint more forward in the midrange and doesn't reproduce the bottom 1/2 octave (20 Hz - 30 Hz).
It's a reference quality headphone system that enables me to listen to music in the evenings without disturbing my family, yet without giving up anything in terms of audio fidelity to the speakers.