These don’t exist. The best you can get is ok HDMI switchers 
I have one that automatically switches to the active source, which is quite nice. I can check the brand when I get home.
I don’t connect my retro consoles via a DAC to HDMI. I just connect over composite or component, depending on which cables are supported. I know people make a big deal about upscaling, etc., but I don’t really care, lol. It works fine for my PS2 and we play it all the time.
Oh, that’s exactly the one I have. Oddly, I had my Steam Deck connected to it and never had issues. But I was going from the Steam Deck through a 130w TB dock, and that might make all the difference in the world.
I vaguely remember looking something up about this issue, and somewhere I read it could possibly have something to do with the length of the HDMI cables. I probably had some longer ones laying around and used those instead of buying new short ones. I ended up getting a bunch of flickering, but only with the Steam Deck.
This feels like a conversation we had on the Steam Deck thread. It feels familiar.
All this is reminding me why I switched to emulation.