What is AV receiver?

In plain language

An AVR takes several HDMI sources, switches between them, extracts and decodes the audio, drives the speakers, and passes the video on to the display. Sitting in the middle, it is a sink to every source and a source to the display.

Why it matters in your setup

Because it is in the middle, its capability handling governs everything upstream. A receiver that only advertises 4K60 will keep a 4K120 television and a 4K120 console from ever finding each other. The same applies to VRR, ALLM and Dolby Vision.

It gets more subtle. Some receivers pass video through at full bandwidth while still advertising their own, lower capability set. The hardware could carry the signal; the negotiation never gets there. And many receivers only support the highest modes on specific HDMI inputs.

This is why the standard advice — connect the console straight to the television and use eARC for sound — works. It removes the receiver from the video path entirely.

What the DR HDMI 8K does with it

The DR HDMI 8K offers the other way round: keep the receiver in the chain and control what the source is told anyway. Place it between the source and the receiver, present the capability set you want, and the source stops taking the receiver's word for what the display can do. The Dolby Vision data block sniffed from the display can be carried through the same way, which is what keeps DV alive with an AVR in the middle.