That's not Oratory's EQ, that's AutoEQ's purely algorithmically generated EQ, using Oratory's measurements, which, as can be seen from the 'Equalized' curve on the graph in your link, in this case has produced an EQ that erroneously boosts the 8-10 kHz region by around 5 dB.
This is Oratory's actual EQ for the HD560S. I would only use AutoEQ's EQs if he hasn't made his own one for a particular headphone, due to the potential for such robo-errors as seen in this case.
Not the same drivers, not the same angle, not the same impedance, not the same group delay, not the same distortion, not the same sound. Claims that
these measurement differences are small, and just down to unit/positional variation are even more absurd than when the same thing was said about the HD600/HD650. Oh and talking of group delay, the thing that's 'messy' is not the HD560S's time-domain behaviour, but a measurement set-up that allows open-back headphone measurements to be polluted by uncontrolled environmental noise, which has nothing to do with the performance of the headphone. This is quite obvious when you notice that open-back headphone group delay measurements on here commonly exhibit 'mess' above 1 kHz, none more so than the least isolating headphones
as measured by Rtings e.g. the (very) open-back
HifiMan Arya, whereas closed-back headphones commonly don't have this mess in their group delay, e.g. one of the most passively isolating closed-back Rtings measured, the
Drop + THX Panda. Note that Rtings'
own group delay measurements of e.g. the Arya do not show any of this mess, because they actually control for this environmental noise by measuring within an acoustic isolation chamber. Also note that this pollution of the measurements on here by environmental noise is not confined only to the group delay measurements, but also shows up in the frequency response plots as
'fine grass' roughness in the same region above 1 kHz (that can also be seen in the HD560S FR, to a lesser extent due to them being more isolating), which again has nothing to do with the acoustic output of the headphones. And even if it wasn't polluted by noise, the group delay plot would still not be fit for purpose, as it's
excess group delay that matters for audibility.
It's the
front volume 'openness'/'closedness' (degree of seal) that really matters when it comes to bass extension. See here:
https://www.reddit.com/r/oratory1990/comments/drn9av/_/f6nuowj
This is a big difference in bass distortion, which I really can't imagine could be down to unit variation. Something's not right here. Even being generous and assuming the distortion SPL figures were at the non-standard 425 Hz, and so from the frequency response this corresponds to +2 dB higher at 1 kHz for each level, the figures don't match up at all. At 95.8 dBSPL @ 1 kHz Oratory measured
0.2% THD at 40 Hz, whereas here at 94 dBSPL @ 425 Hz ~ 96 dBSPL @ 1 kHz (so very close SPL) we have
0.6% at 40 Hz. At 104.8 dBSPL @ 1 kHz Oratory measured ~
0.6% THD at 40 Hz, whereas here at 104 dBSPL @ 425 Hz ~ 106 dBSPL @ 1 kHz (approximately equal SPL) we have ~
1.75% at 40 Hz. And at 113.8 dBSPL @ 1 kHz Oratory measured ~
2.4% THD at 40 Hz, whereas here at 114 dBSPL @ 425 Hz ~ 116 dBSPL @ 1 kHz (comparable SPL) we have over
6% at 40 Hz. As the big discrepancies are largely confined to the bass region, the only explanation I can think of is that a proper seal was not achieved on here, which we've seen before with the HifiMan Ananda's
erroneously high measured bass distortion due to lack of a good seal (as Crinacle
demonstrated with a headphone of similar design, the HifiMan HE1000 V2). One caveat is these latter two are closed front-volume headphones, whereas I believe, like the HD600/650, the HD560S has an open front volume, so the seal-distortion behaviour may not be exactly the same, but I would think there would still be a dependence there.
Rtings' measurements show
excellent frequency response consistency for the HD560S on real heads using in-ear mics, with a maximum variation of just +/- 0.5 dB (ignore above ~350 Hz as that's the point they merge with positionally varied measurements on their non-industry standard rig). The overblown FUD repeated ad nauseum by some that professionally made, properly sealed industry standard ear simulator measurements don't translate to a good guide of on-head bass performance on real humans doesn't apply here.
Most likely. It probably just came loose at some point and so was only partially inserted, which can cause some weird effects.