palmfish
Headphoneus Supremus
The OP said later that she wanted to listen to movies as well through the headamp.
I suggested that in post #48, and she'll still be able to listen to video games that way as well.
The A/V out is two-channel, that's all she needs to hook up to for multiplexed stereo through the headamp; multi-channel in through HDMI, composite stereo audio through the a/v out, aka Analog Audio Out in the feature list (#3, #4, #52).
I agree, if that is indeed an analog out on her AVR, then that will work. It might let her play with DSP modes (neural THX, Dolby headphone, etc.) while listening too.