Equipment & OS:

• Apple TV 2
• Mac Pro (circa 2013 - the cylinder)
• MacOS Sierra Version 10.12.6
• DAC (digital to analog converter, this only has USB and TOSLINK connections)
• HDMI cable connects Mac Pro & Apple TV
• TOSLINK (digital optical) cable connects Apple TV to DAC

What I want to do...

I want to use the Apple TV to stream iTunes music from my MacPro to the DAC which then connects directly to powered speakers.

Previously I have connected an earlier Mac Pro (circa 2009) directly to the DAC via TOSLINK. This worked GREAT! The earlier Mac Pro had a TOSLINK output. The new Mac Pro (2013) doesn't.

Prior to that I has streamed iTunes wirelessly to the Apple TV which in turn connected by TOSLINK to the DAC. This worked GREAT too! When I set up this solution I had a TV monitor available that connected by HDMI to the Apple TV.

Unfortunately, I have no other monitor or TV display available to connect to the Apple TV.

Problems

<< System Preferences >> << Sound >>

If I go to << System Preferences >> << Sound >> and look to "Select a device for sound output" I don't see the Apple TV connection via the HDMI. Note, the Apple TV via the HDMI doesn't show up as an input either.

I do see the Apple TV available for AirPlay, but when I select it a pop-up window appears asking me to: "Enter the AirPlay code for "Apple TV"

I assume the "AirPlay code" is not a "password" for the Apple TV (my Apple ID password doesn't work). I think the pop-up window wants one of those 4 to 6 digit "codes" that pops up on the device to which one wants to connect.

As I don't have a monitor connected to the Apple TV I don't have anything that can display the "AirPlay code".

Seems like the HDMI connection to the Apple TV should get me something, but I can't think of a way to make the Apple TV display appear on the monitors connected to the Mac Pro;-(

Suggestions appreciated.

iTunes

I have similar problems in iTunes. If I open iTunes and try to select an output device, I can select the Apple TV but the same pop-up window requesting the "AirPlay code" that I don't have a way to see appears.

Note: I have a 27" Apple Cinema Display, but it has not way to connect directly to the Apple TV.

Again, any suggestions much appreciated.