How to get audio out of Dell U2711 speakers with 2013 MacPro

As far as I can tell from the Dell website the UZ2711 does not have built-in speakers therefore of course you will not get any sound from it.

Apple disable volume control if the interface being used to send the audio is a digital interface i.e. Displayport or HDMI. Apple assume the output device i.e. monitor, TV or AV Receiver will be responsible for controlling the volume. Apple don't say but I believe their reasoning is as follows.

In order to alter the volume the original sound has to be first converted to an analogue wave form, it is then adjusted. If being sent on via a digital connection it then has to be converted back to digital. The output device in order to output the signal as audible noise has to convert the digital signal to analogue again, if the output device also has a volume control it might also adjust the analogue wave form again. Apple are presumably wanting to avoid this extra set of conversions. If instead the Mac sends the audio unaltered to output device then that extra set of conversions does not have to take place.

Another different matter is that on the classic Mac Pro - Apple for some insanely customer unfriendly reason 😠deliberately disable sending audio over HDMI or Displayport. This can be 'fixed' via a third-party unofficial KEXT driver but recent macOS versions have now gone even further to make this much harder to achieve. It now also involves installing a patched Apple KEXT as well.

So it seems your real problem is the monitor has no speakers. The Mac maybe thinking it does since typically HDMI displays do. To 'fix' this you need to either use the built-in speaker of the Mac Pro or some external speakers. Whilst normal external speakers could be used I believe it should be possible to use Dell's own 'soundbar' for this monitor. See - https://www.dell.com/en-uk/shop/ax510-soundbar-speaker-for-u2412m-ultrasharp-mon itor-and-selected-legacy-monitors/apd/52…

This is designed to clip on to the monitor, get power from the monitor and might automatically get the sound sent to the monitor via the HDMI signal. (If not it can be connected to the Mac 3.5mm output as an external speaker.)

Maybe I can help you?? Yes, DisplayPort won't work for audio, and DVI won't work either. and Yes, it'll work with an HDMI connection only. As to why that is, talk to Dell. Yes, your Mac Pro will support HDMI audio out, but it's tricky, involving the manipulation of a kext file, which I don't know how to do. I'm sure others will, though. For now, this is what I've got:

Open the Monitor's on screen Display, go to Audio settings, choose Line out Source as HDMI, and Audio Configuration as 2.0 (or whatever)

Exit the OSD (on Screen Display)

For Sound :: Go into System preferences from the Apple Menu and Choose "Sound"

click the "Output" tab and look under 'Type' to find the HDMI option, and choose it .

that's all I have.

John B