[LordoftheRingsEE]

-- Yes, it is very clear now, thank you.

* To me, your 'issue' seems to come from the fact that the 5.1 analog RCA and 2-channel stereo XLR connections are two separate entities. ...And they are also going to two different components.

I am not an expert, just a technological thinker and explorer (Audio, and everything else on this planet)..

TRY THIS:

#1. From your Oppo BDP-95: Connect the full 7.1 multichannel analog (RCA) Out to your Cary Cinema 12's full 7.1 multichannel analog (RCA) In.

#2. From your Oppo BDP-95: Connect the stereo analog (XLR balanced) Out to your Cary Cinema 12's stereo analog XLR balanced In.

OR THIS:

1. As above (#1.). ...The full 7.1 analog (RCA) multichannel connection.

2. From your Oppo BDP-95: Connect the stereo XLR out to your Cary SLP-05's stereo XLR In.

3. From your Cary SLP-05: Connect the stereo XLR Out to your Cary Cinema 12's stereo XLR In.

___________

* When you select Digital Coaxial from your DVR (or any Digital input for that matter), now you said that you get 5.1 (digital surround sound) from your DVR. OK. ...Or am I missing some' here?

** If you select 7.1 analog bypass in your Cary Cinema 12 (cinema bypass); for audio purists so that you can bypass all digital conversions for your analog sources (Oppo BDP-95's multichannel analog RCA connections), you are also bypassing the 7.1 multichannel analog input!
=> Turn the Cinema Bypass feature to OFF. ...And see if it will restore the stereo (L/R) audio signal from your Oppo BDP-95's XLR Out to your Cary SLP-05's XLR In.

I'm just trying to help you the best I can here; by recommending different connection's arrangements and settings.
Your particular situation is somehow unique (or not too common), and that's why you have to know what each component does exactly from their settings affecting the audio signals out from the various type of connections; the outputs of your Oppo player, the outputs of your Cary SLP-05 preamp, and the outputs of your Cary Cinema 12 pre/pro.
...All the Outs and Ins. ...Depending of what's connected, and what's selected.

EXPERIMENT with various connections, and settings.

OR, make things SIMPLER, and use only one preamp (Cinema 12). ...For your home theater room.

AND, have a separate Music stereo listening room for your SLP-05, with another Oppo player like the BDP-105 for example, and a high-end turntable with a Phono preamp.

I know I know; you want both in the same room. ...Then, EXPERIMENT.