Gonk: Based upon what I have seen thus far (not a lot), DSX does not appear to prohibit the use of rear surrounds. Consequently, I would love for you please explain how a product that only has 8 DAC's like the AV7005 apparently does, can claim to be 9.x or 11.x, when it can't output that many channels.

In my uneducated way of looking at things, what Marantz is doing would appear to be a misrepresentation if not an outright rip-off.
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Living Room 24x18 open 1/2 flight up to a raised dining room/hall 24x12
Outlaw 976 pre-pro running 5.1 system
Outlaw 750 for Artison Masterpiece LCR and 2 NHT SuperZeros rears
Velodyne Servo FX-1200
LG OLED65C8PUA via HDMI2 to/from 976 HDMI ARC
Roku Ultra
Samsung BD-D5500 BluRay
Amazon FireStick 4K to 976 Aux HDMI input for Amazon Music Ultra