Purchase a receiver or what? need your advice.

Thanks everyone. This set up will be solely for Blueray /4k / Cable Tv / Netflix.

I have a separate 2ch. rig that the Oppo 205 will also be used to listen to music. That consists of... 
Coda CSiB Integrated,
Revel F52 Speakers,
VPI Aries Scout TT with an Ortofon 2m Bronze cart, 
Herron VTPH-1 Phono Stage,
SVS SB-13 Ultra sub,
Teo liquid metal interconnects
and a Morrow Ph-3 cable between the VPI and Herron.

@caphill   "But the Marantz SR8012 has more up-to-date features and formats compatibility (4k with latest HDR Dolby Vision & HDMI version, Dolby Atmos, DTS-X, Auro 3D)."

I do want all the up-to-date do-dads. Along with the Hdmi 2.2 which I understand you must have for true 4k.

Yes, it was the latest AV8805 processor.  I have not directly heard the 8802 or 8803, but I suspect that there really isn't that much difference.  The 8802 was already extremely well designed with large main power supply and a lot of localized power supply capacitors all around the DAC I/V board.  And the "new" version of the Marantz HDAM discrete analog boards.
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I was quite impressed with the AV8805, based on a $4k price tag and expecting the Marantz "warm" signature.  The sound was very full and had a lot of impact and authority (audio percussion and sounds hit with a lot of authority).  That being said, I could tell it was warm with rolled-off highs.  If that was my only exposure to HT processors, I could easily live with it.  It did sound very good.
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That being said, my main proc is Krell S1200U and the Krell basically blew away the Marantz in all ways!  Krell was significantly cleaner in both audio AND video.  Of course audio was not warm sounding and was crystal clear.  However, it was surprising how good the video was on the Krell, since it is just re-transmitting the HDMI signal with the audio stripped out.  With the Marantz, I could tell that the video (through HDMI) was not clean and had a lot of noise.  Images were not as crisp and sharp looking. 

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A lot of this could be explained by the Krell using only linear power supplies (even for digital and video sections).  There isn't any switching power supply in the Krell (even the Foundation uses ONLY LINEAR).  That being said, I think the Marantz warmth could be resolved a lot by placing in a Hi-Fi Tuning Supreme or Silverstar fuse.  That would increase the speed/detail and reduce the warmth, and would probably also increase the sharpness and quality of the HDMI video.

@auxinput

Thanks for sharing your experiences with the AV8805. Did you test it for surround movies (home theater)? I don’t like Audyssey in the Marantz and would prefer ARC2 way better IMO. Even the latest NAD av products no longer use Audyssey, they now use Dirac, which is superior to the Audyssey. Room Perfect is another top notch room correction calibration.

In my dedicated home theater room I’m now using the Lyngdorf MP-50 av processor which uses Room Perfect and its RP implementation is extraordinary. With Room Perfect properly calibrated the surround sound experiences from movies takes to a whole new level in comparison to the Classe SSP 800 that I previously had in my dedicated home theater room.
The RP in the Lyngdorf MP-50 makes huge difference for surround sound home theater application.
Not to mention that the SSP 800 cannot support Dolby Atmos, DTS-X & Auro 3D. Now with the Lyngdorf MP-50 my setup is 7.2.4 with 4 overhead height ceiling speakers for Atmos setup. 

On the video side of thing, I run the video from my Oppo 205 directly to my 4K display using video only HDMI out of the Oppo 205 and run the audio to my AV processor using the audio only HDMI out of the Oppo 205. The Oppo 205 is my only AV video source in my dedicated theater room. I did the same when I was still using the Classe SSP 800.