Help understanding Preout. Use existing/old AVR to add 2 channels to new AVR - Possible? (convert 5.1.2 to 7.1.2)

stevedawg85

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Jun 17, 2014
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New: Denon 3300w 7.2 Atmos (5.1.2)
https://assets.denon.com/assets/images/productimages/AVRX3300W/5_EL_avrx3300w_e3_bk_re.png?RenditionID=1

Old: Onkyo HT-S5100 7.1
http://images.crutchfieldonline.com/ImageHandler/trim/3000/1950/products/2008/580/x580HT5100B-B.jpeg

Is it possible to use use the full 5.1.2 on the Denon AVR and somehow wire the old Onkyo to use 2 channels for the rear to experience 7.1.2?

From what I gathered, I think this is how it'll work, lmk if I'm wrong or how to properly make use out of the old AVR.

My guess:
Use the red/white cable from the pre-out Surround Back on the Denon
Connect the other ends to the Onkyo DVD Surr Back.
Wire up the normal 5.1.2 speakers on the Denon
Wire up the Surr Back on the Onkyo
The Onkyo must be on CD input the entire time

If I'm completely wrong, please help, I don't want to blow anything out by wiring something the wrong way.
 
You can hook it up but unless the menu lets you assign the surround back outputs to Atmos channels and still use the line level surround back as surround back you won't get Atmos height channels. If the menu doesn't grey out some options you can hook it up and see if the test noise comes out of the correct channels.
There are strict requirements on speaker position and directionality for object based surround codecs like Atmos. The upward firing speaker addons they sell won't work nearly the same as ceiling mounted speakers. The other speakers have to be at ear level including side and back surrounds.