HD800 is really not happy as a portable headphone, and as much as it is king for classical and opera, will frustrate you if you mean to listen to it at cafes, on the road, on the subway, on airplanes, and so on. Furthermore, it desperately wants solid amplification. I suspect it would be minimally acceptable with the Chord Mojo, but would sing much more if you fed it Modi Multibit and Vali (1 or 2).
The ridiculous Woo Audio portable tube amp is $700 more than HD800 itself—new!—and for that price, you would be much happier with the stunningly good KSE1500. I have not done an a/b with HD800, but they were clearly superior to my k3003i in terms of detail and soundstage, though I suspect the low end didn't slam as hard, as is expected with electrostatic diaphragms. I have enjoyed k3003i a great deal. Fear not about the knockoffs — I a/b'd mine, and concluded that they were indeed fraudulent, but the sound quality difference was so subtle that it was eclipsed by, for instance, the differences resulting from changing the silicone tips.
The new MySphere may be worth considering, as it is built to be extremely easily driven (by an iPhone, if necessary, though it will sound better as you feed it better source material), though it lacks isolation and is quite expensive.
Finally, N90Q is a very nice package deal, as it has DSP, DAC, and amp all in one package. This has the unpleasant side effect of (like the HomePod) leaving it open to quick obsolescence as DSP, DAC, and I/O technology advances, but is nevertheless the highest-end noise-cancelling headphone out there—perfect for planes and trains and road trips when you are not driving.
Coda: For true bang-for-buck, you're going to want the trusty HD600. Soundstage is not notable, but the tonal quality of the voices especially is just spot on. You can get it new for like $250 or used for under $200. Fulla 1 or 2 would drive it acceptably, though it will scale with whatever source you put in front of it.