Best I have heard the HD800 from different combinations in my gear is:
Aero DAC -> balanced cables -> Luxman P1 -> HD800.
I find no fatigue at all with this combo. Not the least bit. The soundstage is incredible. While I have gotten a good sense of soundstage before with other headphones/gear, with this combo, me, the noob ears, immediately thought "so this is soundstage!". Immense. Almost surround-sound like. However, I still haven't tube-rolled on the M24 DAC, and I forgot to test the BelCanto feeding balanced into the Luxman. But I will do that next week when I get more balanced cables.
Take what I said with a grain of salt, as you should factor in some new Aero DAC love in there, which might bias my opinion a bit.