My experience with using preamp outs on my Marantz:
You will still have :
1-distortion from amp
Theoretically, you bypass the internal amp.
Practically, the amp will follow you to the grave.
The question is why is Anthem refusing to answer 2 legitimate questions? Would another member ask Anthem the same questions and post the answers? I find it suspicious that Anthem refuses to put their answer in writing.
Anthem ignored my following questions.
1- AVM 70 Is HDMI 2.0b?
2- AVM 70 Does it support Dolby Atmos from TV to the unit?( True e ARC)
My guess is the answer to both questions is no. That is why they refuse to answer.