You’re a search ninja 
Thank you so much.
Great to have that table to refer to. I’ve asked Pass for the figures on the preamp, but in the meantime (and if my brain’s at least partly functional) I think you’ve managed to educate a total tech numpty.
As a test…if I had:
XA30.8 — I’d use 0.6V out (rated 0.7 for full power)
XA200.8s — I’d use 2V out (rated 2V for full power)
…provided my speakers meant I was likely ever to want near full power, since otherwise I’d be throwing away oodles of bits to attenuate the DAC’s signal down to something that wouldn’t make my ears bleed.