PERFECT SOLUTION FOR USING AN OLD MAC AS AN AIRPLAY SERVER FOR RECEIVING THE A/V STREAM
The current version 2.04.3 as of 2017-03 supports the newest macOS 10.12.3 Sierra, until back to OS X 10.6 Snow Leopard. Great backward compatibility. If you have no more use for your old device, at least it can act as a secondary display!
Therefore I can use my old Mac running OS X 10.6.8 Sierra as a secondary display for my current rMBP running macOS 10.12.3 Sierra.
Server side (receiving side of the stream): Start the app. Firewall asks you: Allow incoming connections for X-Mirage? Confirm with Yes. You are done! No extra drivers, no restart, no config necessary. It instantly is available on the LAN. If you want you can tweak settings according to your needs (screen size, password, etc).
Client side (sending the stream): Works out of the box with the built-in system features (in the system controls Airplay and Audio you select your destination, where you want to stream to. X-Mirage was properly listed as a stream target. No drivers, nothing. Impressive!
Quality & Speed: Did not evaluate that extensively. But it seemed very ok! Lag almost unnoticable, quality very ok.
With X-MIRAGE I had a working setup in just 1min, and understood it completely after 5min. So different to the competition if you want to connect an old and a new Mac. Before that I spent 4 hours trying out competitor software, which did not work at all connecting the old and the new Mac.
AIRSERVER: It offered downloading a legacy version. But obtaining a trial version was not possible, as the changed the process meanwhile. Tried this and that. It all failed.
AIRSQUIRRELS: Tried their combo of Reflector (server receiving stream) and Airparrot (client sending stream). Airparrot needed to install an audio and a video driver, needed to restart the Mac. Upon connecting from macOS 10.12 with the current Airparrot 2.7 the legacy Reflector 1.6.3 on OS X 10.6 crashed. Tried different version combinations, but all failed.
I don't know whether I will buy X-Mirage, as it is a one time occasion (rehearsal of a keynote presentation on two screens). But should I need it again, I will definitely consider buying it! The least I could do, was to give you a positive review. I was really impressed!