I've heard the Luxman 590AX II and the Accuphase E600, though not the E650, and in different set ups.
I'd vote for Accu, as I found it richer and more full-sounding and, in general, I liked it more. Nevertheless, I think Luxman is very very good as well and you won't go wrong either -but none of them will really give you "tube sound".
PS: I have an Accu A/B int'd amp, so I admit I may be biased, but when I took the Accu I coul choose between it and a Luxman, and... guess what. :)