Looks like you know what you're talking about! Impressive setup.
I'm a bit surprised you find the HD800S that good though. Sure these are fine headphones but the more time I spend with mine, the more I find the bass to be ... not so good. I recently bought Earsonics Velvet IEM and wow, it became clear what I was missing with the HD800S. In comparison, the bass is slow, poorly defined and totally lacks physical impact (T1.2 or Audeze cans are better at this too). The rest is top notch but for a reference level headphone, it is underwhelming. Maybe they are just not for me and I would be better off with the new Focal Elear or maybe it's my setup but I doubt it. While not crazy high end, it's not slouch either. Yggy + Taurus MK2 fed by Audirvana in USB. Balanced obviously. Thoughts?
I understand your point, trust me. I also have the LCD-X and am likely going to part with them. I have nothing against them and find them superb, however, just about every headphone (and big system for that matter) is somewhat of a compromise of priorities. Anyone who tells you different, IMHO, is full of it. Usually what I like to do is be honest, understand nothing is perfect, no matter how much money you throw at it. My first priority is accuracy (a somewhat broad term with many meanings to all which I won't delve into here as to my meaning) and second is sound stage and the ability to transport you to the event, whether the studio or performance. It is rare to find a speaker, headphone and more importantly a system that can do both. That is why I finally settled on the Nola Concert Grands in my big system and have it so dialed in (of course big systems are totally room dependent and too few people understand that and throw big bucks at equipment that can never overcome room shortfalls and why so many churn and are never happy) that when people hear it they leave amazed. Is it "perfect", of course not, despite the huge cash I have into my system; however little has changed in my big system for the last 4 years as it is just that good. I don't think I could do better, at least given my preferences, as well as those who hear it.
Back to the HD800s. I was no fan of the HD800 and found the LCD-X preferable to the HD800. I can't just blame the headphone as back in the day when I first got into cans, I was driving both with a HUGO, while good, didn't really do the HD800 justice but was more than adequate and quite good on the LCD-X. Then came the HD800s with the hyperbole of "what was fixed" so I got them on a 60 day money back guarantee from Crutchfield (after first being sent a used pair from Amazon). I was lucky enough to have taken delivery of the Cavalli Liquid Carbon prior to the time (with the guarantee of an upgrade to the Lau if I wanted) and a long demo of the iFi Pro Can amp. I was literally blown away by both. Yes the HD800s lacked the low end definition of the LCD-X BUT when trying the HD800s with these new amps I knew I was listening to something very very special that I have rarely experienced before except in my big system. Having said the above, I was truly enjoying both cans. Along comes the Lau and it is in another league. Is the bass of the HD800s "perfect"? No. Does it have amazing articulation and a sense of being there when driven by the Lau, absolutely. A total transformation and illustration of how good these headphones can be when the Lau showed up. They are more than capable of producing excellent and very accurate bass with the right equipment, maybe just not with the punch of some of the others, which I personally do not miss when the whole picture is considered as the sum of the parts is just so much better than any one aspect of these headphones. I was in this business back in the 80s and have been into this stuff since, although headphones only in the last 4 years, but I know when I have a system dialed in to my liking and with the HD800s, T&A DAC DSD/Mojo and Cavalli Lau I got it.
There is no right or wrong answer just a matter of taste of the individual. There are no absolutes. If the HD800s doesn't meet your needs with the system you have or anticipating on getting don't waste your time with my or others' preferences and opinions. I also live by the tenet that I am never married to anything and hence when I give an opinion, it is not a justification or rationalization of my purchases, just an honest opinion as I never buy anything that I am afraid to walk away from if I don't like it. I really find the HD800s in my current setup kind of ephemeral like my big system that just allows me to lose myself in the venue. When your system allows you to do that it is a special system.
. No need to invest more for now. Enjoy your combo, You'll need to save money for a real upgrade 
(and happily say 800S dont have the same ringing as the 800 did)
