Better 2-channel music

Phil,
I'm not sure I would buy an 851 new. A used 850 will sound great. Other things that pop into my head are mainly circling around overkill. If you are doing 2 channel through a Cambridge, an oppo 103 will do just fine for theater and save you a bundle. That's savings #1. Also, if you have a Cambridge and Oppo, there's really not much that you need out of the Marantz, is there? Just 5 channel volume and maybe different modes. The Emotiva mc200 or outlaw will do the same very nicely and do a darn good job of it. Savings #2.
I know that my Emotiva passes a pure audio signal through very clearly without any coloration. (the marantz 7007 may do this too?) So, I'd say both the Cambridge and/or Oppo could run audio direct mode. You won't need a 2 channel pre-amp. Savings #3.
Now that you have saved money, blow the whole load on a really killer multichannel amp. The Emotiva amps are nice and a great value but not in the class of Mac, Classe and some others in the $5k range.

So, where would I start if I were you? Buy a nice 2 channel CD or DAC-Cambridge is awesome. Try this on CD direct on the Marantz. After that, try borrowing pieces. I think you might be surprised where the upgrades will come from after that.

My theater: Emotiva UMC200, Oppo 105, Dishnetwork, Mac 5 channel amp, coincident speakers all around, velodyne sub and a sota table with sumo phono pre for analogue. I also run my laptop with foobar through a music fidelity for streaming. Don't forget nordost cabling and PS Audio conditioners.

I will buy the Cambridge 851C now. It's $1800 but I can keep it for a long time. Hold on the Marantz AV8801 or AV8802 now to try the 851 with my SR7007. Do you think Emotiva XMC-1 is worth the price increase? I can buy now for $2000 with summer sale and e-club. Mac amps are nice but cost 10 times. Emotiva XPA-1s and XPA-5 are only $2500. They deliver enough juice and pretty clean. What dpecific model of PS Audio Conditioner do you recommend? I don't think I can afford Nordost cables. :)

The Mac adds a little warmth and perhaps some depth. The XPA is a ton of clean power for the money. In my system I need a warmer sound and really enjoy some serious depth to my music. But yes, it is expensive.
The XMC is a great piece and will do wonders for theater. Is it better than 103 and 7007 combo, I'm not sure? You need to try some borrowed pieces. The other option is to eventually but the xmc knowing that you have 30 days to return it. The return shipping is nothing compared to getting to test it.
Will the xmc beat the 851 for 2 channel? I really doubt it! I think the 851 run in direct mode through the 7007 will sound phenomenal. Great way to start. Take your time and one piece at a time.
Buy the XMC when you get a 4k tv...just my opinion.

I'll post pics of my new listening room later in the week. We just put in a heavily reinforced ceiling, some sound treatment and all new wiring. Painting it on Monday or Tuesday.

Thank you Elevick. I take your advice and hold on the Marantz AV8801 or AV8802 but try the Cambridge 851C first. Crutchfield has 60 days to try.

Zd542 and/or Elevick. How would you compare the quality of movie sound between the Marantz AV8801 and Marantz SR7007 using 7 channel output to a 7 channel power amp? Would the difference be significant?