Upgrading your home theater receiver may be due to the need to switch from 1080p to 4k as most older AVR devices don't support 4K transmission via HDMI. However, this only makes sense if you recently purchased a 4K projector or television and have access to a wide range of 4K content.
Most 4K-compatible receivers on the market today can carry a 4K bandwidth signal using HDMI 2.0, but what you should be looking for is an AVR with an HDMI 2.1 port that is HDCP 2.2 compliant.
HDCP is an HDMI feature that stands for High-Bandwidth Digital Content Protection, with 2.3 as the latest version of HDCP. It's a copy-protected tool for 4K UHD broadcasts, but for this to work, you'll need a range of sources and displays capable of it.
With HDMI 2.1 and HDCP ports, you'll be future-proof as you can stream 8K content as soon as it's available to users around the world as you're also eligible for future firmware upgrades. But with the release of future game consoles like PSK supporting 8k, it would be a step forward to have a receiver that can broadcast 8k content.
When choosing an HDCP 2.2 receiver, you should also pay attention to the baud rate / transmission speed it can support via HDMI 2.0 or HDMI 2.1 and HDMI 2.0a connections for HDR content.
However, if you are not ready to upgrade due to 4K but have access to 4K content and a 4-way display, you can put your content directly into the display and bypass the receiver. You can then run the audio cable from source to receiver for audio processing.
This also applies to smart TVs, which are now suitable for most 4K streaming needs. In this case, you can use HDMI ARC to carry audio to and from your TV and receiver. But at some point you may need to upgrade by adding more 4K sources to your home theater setup.
