In the Mac, at the HDMI, in Format set it as Encoded Digital Audio, the Hz setting is irrelevant.Previously my instructions stopped here.In the amp, make sure that the input HDMI is decoding multi-channel audio as expected.Confirm that the speaker setup is correct and click the speakers to confirm that test tone does not output as expected.In the Mac, set HDMI to Use this device for sound output and Play alerts and sound effects trough this device.But anyway, here are my steps with Audio MIDI Setup utility: For some reason they don't match or they do match and there is very little I can do to control it. There must be something going on at the amp end and something else going on at the Mac end. The problem is, that I cannot get it back to the broken mode again, it simply stays fully functional no matter what I do. Here is what I did to get proper 5.1 channel sound working from my Mac Mini. So there will be a lot of processing at the amp, why not declare itself as the destination for the Mac. Anyway, the amp has to pick up the audio signal to be sent to loudspeakers and do a stereo mixdown of a multi-channel signal to be sent for the TV. If you'd ask me, Onkyo's solution is much better than Yamaha's. The only explanation for this is, that my Yamaha takes the TV's spec from the HDMI and proxies it to the Mac and his Onkyo doesn't take anything, it simply presents itself as the destination. Totally different from what my Mac displays.

Whoa! His Mac Mini displays his A/V amp as the HDMI destination. Here is another screen capture of Audio MIDI setup from my brother's computer: The Audio MIDI setup clearly displays as Sony TV being the HDMI output device. The problem, like presented earlier is depicted here: The previous attempt can be found here. All the information I can find on this subject shows that for some people multi-channel audio works fine, nothing special is required, but then again for some of us this is a pain and its almost impossible to get this working. This is my 2nd attempt of trying to clarify how to get Dolby Digital 5.1 output via HDMI.

Imac digital audio output