The Marantz is a bland amp. I would try the following, and as @kofibaffour said, no beast needed:
Quad Vena - very musical, and gets everything just right
Vincent Audio SV-500 - more detailed than the Quad, maybe less fun
Creek Evo or Voyage - a bit dry but flawless in every other way.
Audiolab as well, but I only know it from showrooms and reviews. The others I have owned/auditioned for weeks and months. I know this is way below your price range. I have no experience with anything north of 2K. If my ears voted they would ask for the $800 Quad Vena.