Getting started, need amp recommendation

I recently tossed out my 15 year old Pioneer speakers and stepped up to a gently used pair of Paradigm Mini Monitors. BIG improvement! Needless to say, these are a bit more revealing of the (lack of) quality of my other components. Next on the chopping block is my old Kenwood receiver. I have been looking into units from NAD, Rotel, and the Acurus DIA-100. In the sub $400 price range, has anyone got a recommendation for a used integrated amp or possibly receiver for a newbie with mini monitors? This is my first foray outside Circuit City-level of components, and I would appreciate some guidance. I like the detailed nature of the Paradigms, but I can imagine that a bright sounding amp could get a little annoying with them. Maybe it's just the contrast with my previous speakers that I hear.
Thanks!