The back of the owner's manual has recommended settings for "tube grind" (something like that - can't remember the exact wording). But the settings have the input slammed (all the way up), and everything else mostly flat, except a big scoop out of the mid-mids ...and then setting the damping to low.
So I tried that in hopes that it would do that wooly "everything-rattling" thing that my BB750 does (and with the back set to 2-ohms into a 4-ohm cab to get the earlier power amp clipping).
...and there it was!!! Pretty much identical.
I played with the damping & think the mid setting is closer. Also tried backing off the input a bit to dial back the fuzz a little. Oh and that preset has the HPF turned up a bit - played with that too.
I had it stacked on top of my BB750, and a/b'd them into the Subway 2x15 - and with those settings was damn-near indistinguishable. And that's the "Mesa thing" that made me fall in love with the BB750 originally.
Went back to the D-800+, and it just doesn't do that. The great thing about the D-800+ is that it is lighter and sleeker, and has a nice smooth round tone. But it doesn't have that same BB750 drool-inducing aggressiveness.