Given the poor results in the group delay department we are used to see from other Mfr I wouldn't mind getting a little bit worser that means little more reflections and resonances ...... if it makes it more towards 300€ region for Sundara peers.
The 'poor results in the group delay department' seen on here are most often simply due a measurement set-up that allows open-back headphone measurements to be polluted by uncontrolled environmental noise (and possibly acoustic crosstalk due to using stereo test signals), 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 in the treble
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. As noted by Jude in his
review of the Expanse, these headphones are actually quite isolating for an 'open-back' design, which explains the minimal 'mess' in their group delay. Also note that this pollution of the measurements on here by 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, 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.