Surface Pro has no sound when external display is connected

This procedure actually worked!  What a pain in the app...  So typical of MS to suggest this is a little known problem.

The microphones are a pain in the app too.  Try using a wireless solution like Cisco  Intelligent Proximity on an SP4.  You need to plug in a headset and unplug it just to force the array to switch to get the microphone to work and pick up the ultrasonic token so you can attach to your AP.  Some systems actually stay attached after that while others come and go.  I digress....

Yes, rebooting did work for me, but it's frustrating that there is no "hot swap", for want of a better term.

As discovered by brun.ws in the other Surface Pro audio thread, you can also try the following:

1. Right click on the start button, and select "Device Manager."
2. Look for "Sound, video, and game controllers," and expand its section.
3. Right click on "Intel(R) Display Audio," and select "Disable."
4. Then right click it again, this time selecting "Enable."

It worked for me as well, but I still don't regard this problem as solved. It looks very much like a driver bug to me.

After confirming that the problem exists with the Microsoft adapter as well, I called Surface support today, who directed me to the Surface Pro 4 driver download page. I'll try them in a few hours and then we'll see if those drivers are different from the ones that I have received through WU, but that would indicate some other problem with the update process.

Edit: I tried the suggested drivers, and they are identical to those I have already, so of course the problem remains.

Despite the fact that I've had this problem since day one on three different SP4 devices, two HDMI adapters (one Microsoft) and numerous TV:s and receivers, Surface support maintains that this is a very rare problem that basically affects nobody. Huh. I guess none of us should play the lottery then, because there's a lot of bad luck in these threads. :)

Yes, rebooting did work for me, but it's frustrating that there is no "hot swap", for want of a better term.

I bit too late but I found that by restarting the computer/tablet/device while being connected to the monitor, it finally gives the option to change the sound to the display. This worked with my surface book... no need to install anything or change anything in settings.