NAD C370 with Wharfedale Diamond 9.1's

What do you guys think of this combo? Should I go for a used C370 for around $400 or a new C320BEE for the same price? Is the C370 overkill ?? How big of a difference is there between the two? Should I be wary of buying a used amp??

Any other good used recommendations around or less than $400 that would match well with these spearkers?

(Heard good things about Auido Refinement Complete but I think it's just beyond this price range)