I was linked to this thread via PM, saying there's links in it somewhere to a study on equalizing all headphones to sound the same, looks like this was it.
Originally Posted by udauda
Back to the subject:
How far can EQ really go towards truly equalizing headphones?
Take a look at these papers:
Even with a 200-tap FIR filter @ 44.1 kHz, which is of a rather poor quality, the author was able to match the sound quality of a poor quality headphone to that of a high quality headphone subjectively. Thus, in conclusion, as long as the filter is not a linear phase(pre-ringing) & there's no excursion issue, you can freely equalize headphones however you see them fit.
Looking at it now...
From what I can tell, they used a STAX Lambda Pro to simulate other headphones, and asked the participants to rate the sound quality subjectively.
They then compiled the ratings, and found that the averages were well correlated to eachother, so the perceptions of the simulations by the participants were fairly uniform.
In the conclusions section (second document) it says "One most important results of this study is the finding that the quality of a headphone of poor or fair quality can be considerably improved simply by simulating on it the acoustical characteristics of an excellent headphone".
Which headphone did they use of poor or fair quality? I'm trying to read all of it, and I can only see reference to them using a single headphone in the whole test, the STAX Lambda Pro.