While I don't have enough data to support this assertion, it seems that headphones with badly matched drivers tend to sound bad. They end up having the worst of either channel. Two good examples I can think of are the T1 and LCD2. I've heard some good sounding ones bad sounding ones (this is all anecdotal of course.) Take for instance the following T1 and LCD2r1 samples (BTW, some of the other admins/mods have heard these.)

Beyer T1 with badly matched drivers:


Beyer "Good" T1


The T1 with the badly matched driver sounded bright, thin, and lacking in bass. Although there's nothing in the FR that would necessarily indicate such, especially when compared to the "good" T1 below. Maybe the human brain/ear mechanism hears the worst of both channels (the relative treble plateau on the left channel and the high midrange plateau of the right channel.)

Audeze LCD2 r1 with badly matched drivers


Audeze "Good" LCD2r1


LCD2s, especially the revision 1s, are known to have a very shelved down high-midrange and treble - and be sound very pleasant for forgiving. The ringing on the r1 above wasn't necessarily excessive, but the badly matched unit above sounded hollow and thin.  There was quite a lot of harshness and the bad kind of sibilance with vocals, even on male voice. I suspect the ringing at 6.5kHz and 8.5kHz (not shown explicitly in the FR graphs here, but on the CSD plots) contributes to a double whammy where the ear/brain mechanism end up hearing both - and at their full glory too. The differences in the bad r1 measured above seem to far apart to be accounted for by pads and placement on the measurement rig.

Of all the headphones I've heard and measured, these two stood out as particularly bad, that is not typical and not representative of other samples, during subjective listening tests. I think it's interesting what we see in the measurements of these.

BTW, I think it's rather unacceptable for ~$1000+ headphones to have such poor QA.