I guess I will throw in my two cents with respect to the final tuning of the HD8XX. To be clear, I've been slightly involved in the tuning process of them. The prior HD8XX was pretty good already; but understandably I think people wanted more; and the folks at Drop wanted more. Something more evolutionary rather than a mere tweak. Well this is it. Well over tens ago, maybe around twelve, there was a rumor going around that Sennheiser would release a successor to the HD800. That this HD800 successor would not be bright, but be voiced like the HD650 or even the Audezes, but have the technicalities, fine detail, soundstage, etc. of the HD800. Instead we got the HD700. (Let's not dwell on the HD700.)
Well now I honestly believe that we have it. This the truly the HD800(S) for the folks who do no like the tonal signature of the HD800(S), but appreciate everything else it can do. During my time with the sample (one of many of which this turned out to be the production version), I thoroughly enjoyed every minute. Wait I thought - this possibly can't be anything based on the HD800(S) - it's not bright at all! I found a headphone which was very even except for a scoop in the mids around 2.5kHz. This worked perfectly for me because this dip works for a lot of naturally mic'd recordings where there is excess reverberation. The v2 also takes a nice touch from the prior iteration with a small bump in the lower mids to add some fullness and body to the sound.
I don't think I need to gush about the soundstage, the retrieval of low level information, the dynamics and slammin' bass (when used with appropriate amplification). The change in tonal signature did not affect the technicalities one single bit. And also, no there are no clumsy mods. No pieces of foam, liner, whatever nonsense. Drop pulled off a BIG ONE here! They weren't totally successful the first time around, but this second time, they hit it out of the park.
Drop x Sennheiser HD8XXv2
Drop x Sennheiser HD8XXv2 (BLU/RED) vs HD800S Anniversary Edition (GRN)
HD(db) vs Frequency at Various SPL
Nice pattern here with H2 > H3 > H4. Note that H4 barely moves up. The second harmonic, H2 moves up a bit in the upper mids with increasing volume. I've always wondered if this has to do with diffractions and reflections the cup design - it doesn't seem to be a concern from an audibility point of view. H3 which I personally feel is substantially worse sounding than H2, stays fairly low and only goes up at higher volumes. Note that H3 of the HD8XX is a little bit less than H3 of the HD800S (measurements not shown).
One thing to note is placement. I ensured the driver was as far forward and low as possible. Otherwise the highs can be brighter would be suggested by the FR measurements. There's plenty of wiggle room with the HD8XX cup design to adjust accordingly. It's not perfect - there's still that dip. But as I mentioned, it's at least in a good spot, especially for those who listen to naturally mic'd classical or chamber music where there is a lot of room reverb.
I feel a bit more reserved than usual writing this review; but yeah, this is really fantastic. I think it's because it's been a long long time waiting. Imma gonna order one for myself!