Hi,
I have a JRiver mac mini music only server using HDMI and had the problem of the HDMI output being lost when the video part of my system was powered off. (I also use my system for movies via other sources but after turning my projector off the HDMI audio from my music server would be lost.) (Many music only servers do not use HDMI output but I listen to multi channel high res files so HDMI is the only solution I know.)
SwitchresX solved the problem. HDMI audio is interrupted when I turn my projector off but I can restart playback immediately.
I had tried a hardware dongle for EDID emulation and pass through but it didn't work. I prefer the software solution anyway.
SwitchresX is $16 and other free apps may work ... I think SetresX has an older free version. But, since it works I think I'll purchase SwitchresX
Edit= The free app EasyRes from the app store also works so I won't be buying SwitchresX. As far as setup all I did was install it and tell it to load at login.
-Brian