A while back I bought an M1 iMac and I have loved it. I’ve always been cautious of buying an all-in-one machine because of legacy concerns, but it was just such a lovely package that I got it.
Roll forward to 2025, and I bought a Mac Studio, effectively making my iMac obsolete. But its display is incredible and buying a new display of comparable quality would cost more than the sale value of the iMac.
I tried Luna Display, AirPlay and other options, but was never satisfied. Then, ironically, whilst testing Luna with a wired connection, I discovered something surprising and delightful.
AirPlay supports wired connections using a USB-C cable. Obvious really, it’s right there in the name, AirPlay.
Having decided to share this mind-blowing knowledge, I decided to get some evidence and, whilst I am convinced I have seen an Apple article mentioning this, I am becoming more and more convinced I’m losing my mind. I cannot find it; ChatGPT cannot find it. Claude. Perplexity. Nothing. So, having recorded a 90-second version of this piece, I went back to the drawing board and I did a hardware test (although see the citations for an after-the-fact update).
I have my iMac connected to my Studio using a Thunderbolt 4 cable. The iMac shows up in Displays in System Settings. Great. I can choose to Mirror or Extend to the iMac, and that is surprising enough for people.
But I’m talking about using a cable, so I went to the iMac and turned off WiFi. The iMac still showed as a display.
I then disconnected the cable, and the iMac disappeared as a display option.
Plug the cable back in, and it comes back.
So, what’s going on? I have BetterDisplay installed, after Allison had sung its praises recently I think, so I had a look there, and it shows the iMac and lists it as an AirPlay display. Great. That confirms it is AirPlay, but no WiFi.
It turns out AirPlay does not need the air to let you play. AirPlay, as documented online, works over other connections, reducing latency.
So, here are the steps you need:
- own an iMac you feel like you want to repurpose
- in System Settings on the iMac, go to General → AirDrop & Continuity and enable AirPlay Receiver
- optionally connect the two computers using a USB-C or Thunderbolt cable
- in System Settings on the main computer, go to Displays and down by the bottom right you should see a plus button that lets you connect to the iMac
In my use, which has been months, it is rock solid, low latency (I don’t play games), good frame rate, and high-quality image. It looks better than the Dell monitor that remains my primary display.
Citations
Apple support article: Extend or mirror your Mac desktop across multiple displays
https://support.apple.com/en-gb/guide/mac-help/mchlb5f905a1/26/mac/26
Final update: I eventually found something online, with the 9to5 article being the most mainstream, at https://9to5mac.com/2021/06/20/macos-monterey-airplay-to-mac/:
Send wired or wirelessly
AirPlay works both wirelessly and wired using USB. A wired connection is useful when you want to ensure that there’s no latency or you don’t have access to Wi-Fi.
There’s also a copy of the macOS Monterey page at web.archive.org that has the same quote.
https://web.archive.org/web/20211025191413/https://www.apple.com/macos/monterey/features/
It seems it was planned as a thing for Monterey, then appears to have not really been pushed, and exists in a kind of limbo. It works, and that’ll do for me. But perhaps the problem is that it does not remove latency, and Apple just decided it’s not enough for them to push.
I don’t understand how there could be latency if your connecting the iMac via thunderbolt. But you’re right the Apple forums are all talking about how this isn’t possible when it’s been possible to do since Monterey. I’m about to try to use a 24” m1 iMac as a third external display via my Thunderbolt Dell hub that has a free Thunderbolt port. If that doesn’t work I’m going to try to do it through the main port on the computer itself. You don’t mention if you’re getting the full retina resolution of the iMac though.
It does seem kind of odd considering the throughput of Thunderbolt, but there’s always some latency (hence gamers spending money on low-latency monitors). The questions are really if it is noticeable to an individual, and if so, is it annoying.
Personally I run it at quite a modest resolution because I like to have my monitors far back on the desk, but it does go high. I’m extending from my Studio and have this up on the iMac right now, and the settings say I can go up to 3840×2160.