My son (the "sound engineer") and I have discussed the variation in speakers, headphones, ear buds and room acoustics at length.

Besides the above variations, the primary need for an equalizer is because not everyone has the same ability to hear in different frequency ranges due to genetics, prior exposure to loud sounds, age, etc.

Using an equalizer provides a means for achieving pleasurable listening despite these variations--though I sometimes think that the most important sound control is the volume. ;-v

Not knowing enough of the "innards" of the N8xx--is the DSP chip/circuit in the device smart enough for high-bit-rate compensations through hardware (i.e. equalization through simple parameter changes rather than software compensation)?