LennonNZ: You are correct..
If you have TV+AMP you would plug TV into AMP via HDMI and any sound you play on the TV (Freeview or an input on one of the other HDMI ports on the TV) will be send back to the AMP via HDMI cable to play on the external speakers.
If you had say PS4 plugged into the AMP it would play the sound on the external speakers. If you had a PS4 plugged into another HDMI port on the TV it will send to the AMP via the HDMI
If you had a sound bar only then the sound would be send to the sound bar via HDMI.
I have mine HT Set up as.
TV - HDMI 1 (ARC Compatible) - to Onkyo AMP
TV - HDMI 2 (PS4)
TV - HDMI 3 (XBOX One)
Onkyo AMP (Output) to HDMI 1 of TV
Onkyo AMP (HDMI Input 1) - SKYHD
Onkyo AMP (HDMI Input 2) - PS3
Onkyo AMP (HDMI Input 3) - Xbox 360
Onkyo AMP (HDMI Input 4) - Apple TV
Onkyo AMP (HDMI Input 5) - Rasberry PI
Onkyo AMP (HDMI Input 6) - Igloo
If I watch Freeview/PS4/XboxOne the sound will be sent to the AMP via ARC Protocol across the HDMI to play on external speakers on the AMP.
Any input I choose on the Onkyo AMP, sound will come out of external speakers and video will be send to the TV to show it.
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