Can you please elaborate on that a little? Are you saying that some headphones simply refuse to accept a boost in that region or that they distort? My LCD2C has a dip in that region, but the headphone responds well to EQ in that area
In addition to sounding definitively clearer than stock, I also don't notice any weird distortion. The distortion measurements back this up, showing what is still impressively low distortion in that region:
I've never actually run into problems EQ'ing in the high midrange and low treble. Where I do sometimes find difficulties is in increasing bass on open-backed dynamics with high bass distortion, and with trying to add high treble to balanced armatures that just physically can't reproduce the highest frequencies.
Ah but the LCD2 (with its huge linear dynamic range) isn't a turd.
It reacts well to EQ.
With some headphones that have issues in the area to be EQ'ed the results are always disappointing. High amounts of distortion. You can get it tonally more balanced in that case but won't sound great.
As you mentioned... when too much EQ is needed or a headphone simply isn't up to it the results are disappointing.
The EARS is fine.. the 'standard' correction that comes with it is wrong IMO.
I know Marv is trying to improve on it. For the range above 500Hz he is doing a much better job, below 500Hz mini DSP is much more accurate.
Edit: Noticed he recently made some adjustments in the lower FR part and think his compensation is MUCH better than that of mini DSP itself.