I've had the poor image quality problem with Macs and Dell displays for ages. My go-to fix that usually works is to generate a custom EDID profile for the monit

I've had the poor image quality problem with Macs and Dell displays for ages. My go-to fix that usually works is to generate a custom EDID profile for the monitor that lets it negotiate to use RGB signalling rather that YPbPr 4:2:2 crap. I think Apple does this on purpose. LG displays seem to work out of the box. I Googled "Mac EDID ruby"[0] to try to find the script that I'd found and used. [0] https://embdev.net/topic/284710 https://embdev.net/topic/284710