Does your amp support CEC? If so, you could make sure it is turned on for both ATV and the amp and just use the “HDMI” setting in the ATV settings.
Also, just to confirm—in the ATV’s remote>volume control settings, do you have it set to control the receiver via IR?
This isn’t a big deal.
If you’re developing in Xcode, you did not buy an 8GB Mac in the last 10-years.
If you are just using your Mac for Facebook and email, I don’t think you know what RAM is.
If you know what RAM is, and you bought an 8GB Mac in the last 10-years, then you are likely self-aware of your limited demands and/or made an informed compromise.