l recently listened to the 800 with the HDVD800 amp (and others). l tried them in different places, different days... basically, l listened to them extensively. IMO, they definitely have a larger soundstage than the little brother, easily noticeable. Clarity wise, l can't tell, l didn't pay attention to that feature (l would say they must be somehow in par, sort of equal). But make no mistake: to my ears, the 800s sound is surely l few steps higher than the 700. lt was simply more 'right' or 'mature'... (sorry for the vague terms).
l was going to buy a pair this year, but then l thought of getting a WA 2... Besides, my 700 are so new, that l feel bad about buying the 800 and keeping the 700 in a vitrine... In any case, we'll see what l end up buying
Oh, by the way, l agree 100% with those who claim that to really get to know the 800 you need:
1- Good amplification
2- Extended time with them
l had previously listened to the 800 twice: once with a good set up, but only for a while (in San Francisco); then, for longer, but only out of my Fiio X3. l was unimpressed... Until l sat down to listen to them again, with time ahead and TOTL amplification. l would suggest you take these 2 factors into account in order to judge that HP