I've got a case of upgraditis too, and have been considering a new integrated. I'd suggest putting the Parasound Halo integrated on your short list. Stereophile recommends it as an "A" level product. it has a well regarded dac section as well, so you could use your Marantz as a transport, and let the Halo do the decoding.
It's not cheap, but open box deals can be had at Audio Advisor and Safe Soundhq.
It's not cheap, but open box deals can be had at Audio Advisor and Safe Soundhq.