Is there a thread explaining or showing your measurement apparatus? I've never seen a measurement technique that produces a 'flat' raw ideal for headphones.

Here is a pic (the one with the Sephora box):



It produces these:

http://www.changstar.com/index.php/topic,987.msg35940.html#msg35940

IMO the key is to use materials that minimize internal reflections, and to be careful about seal when headphones require it. Note the rig does not employ an ear simulator (I only use that for IEMs), therefore compensation is less of a requirement, and measurements tend to be more repeatable in the higher frequencies.

From what I understand of human hearing and the recording process, surely a dip of >10dB around 2-5.5khz would cause a serious problem with diction in vocals (particularly "K", "t", "Ch" and "ss"). I've never had that problem with Stax (except an underpowered 007 MK2) - if anything, I've had the opposite. Granted, this could be a new change from the older lambdas - which are the only lambdas I have used.

Thanks.

I actually felt some vocals seemed behind some instruments with the 307s (again, spent more time with those). I don't necessarily think one would experience sibilance and similar issues. Note 2k and bellow are actually above or close to the levels in the treble region...

You are more than welcome to give more credit to these measurements of the perhaps somewhat similar 507 if you like:

http://www.innerfidelity.com/images/StaxSR507SE11049.pdf

They also show a 10 dB drop from 2 to about 8 kHz and which are probably closer to my 307 measurements (minus the null around 4.5k which I think is a measurement artifact - perhaps a reflection that the foam material inside the measurement was not able to properly absorb).

Futhermore, though perhaps there are certain similarities, I don't feel the 007 MK2 sounds or measures the same as the Lambdas (old or new), under or over powered, so I wouldn't group individual headphone issues or assets with all things Stax. If you are comparing to the old Lambdas, I guess I wouldn't know for certain (I think I heard a pair at THE Show some time ago). However, here are some impressions and measurements of the older SR404s which seem kind of similar what I got with these and the 307s:

http://www.changstar.com/index.php/topic,352.msg5581.html#msg5581

More measurements of the SR404s here:

http://www.innerfidelity.com/images/StaxSR404S2742.pdf

No worries. I think measurements should at this point be interpreted in relative terms. If it helps, I measured these cans as I measure every can that requires seal...