What you are proposing, in essence, is upgrading from very nice consumer gear to specialist hi-end. The parts and designs in hi-end gear result in better sound quality (generally speaking) due to many factors, but among them are the power supply and the analog outputs. Those who design this gear are relying heavily on the "art" side of engineering (listening) and use measurements as an aide.
There are many, many factors involved here, but MOST importantly is your media room. Are going to position the speakers properly? Will your main listening position (sweet spot) be positioned ideallly? Will you make an effort at some point to acoustically treat the room? You can blow all the money you want on gear, but if the couch is pinned against the back wall and the speakers are stuck against the front wall or near the side walls (or in the corners! ugh) then you will never hear what you paid for.
As for the gear, there are trade-offs. The new Marantz AV8801 is going to work virtually flawlessly. You can run Audyssey and call it a day. On the downside, this flagship does not have the analog output design that you will find in, say, a Cary Cinema 12 or a Bryston SP-3 (or presumably a Mac). Nor will the Marantz have a DAC implementation of a Bryston. Nor will it have the power supply design. Etc. But.....you are now getting into "boutique" gear. If you believe that Audyssey performs some kind of magic which you can't live without, then forget about hi-end. I would NEVER eq a great pre-amp and amp driving great speakers. Trims and delays...bass management, etc for home theater...sure. But not EQ. That's why cylinder bass traps are for. And a rug. And proper speaker positioning.
HT: Panasonic BDT 460 | JVC RS600 | 106" x 45" Stewart ST 100 | Marantz AV7005 | NAD M27 | Elac Uni-Fi UF5, UC5, Debut B6 | Focal CMS Sub
Stereo: Cary Audio 306 SACD Pro | Cary Audio SLP-05 tube line level | Cary Audio SA-200.2 | Focal Diablo Utopia III
Den: Panasonic BDT 220 | 60" Panasonic VT60