The krell I think, especially if it's a used one 'cos the second hand value plummets nicely to its true new US value (around £1200-1300). The 400xi eats a Naim for breakfast, although the latter sells because it's a Naim 
Accuphase (and current Luxman) amps all seem to me all be fur coat and no knickers - beautiful and lavishly specified with that legendary build and "feel," but sounding very uninspiring compared to UK home grown amps like a Rega Elicit, LFD or Croft, let alone a Sugden.....
Just my views, of course
but ask HiFi dave, as he's had 'em all at some point...
I can't go on and I can't go back, I don't feel so matter of fact,
I tried and tried to make good sense, What's the good to try it all again?