Use AK100 as USB DAC and Optical Output to Amplifier

[jmacdonough]

So, my brother gave me an older Astell & Kern AK100 Digital Audio Player, and I wanted to see if I could use it as a DAC to output audio from my PC into my stereo.  Here's how I set it up:

 

USB from PC into AK100 > Use As USB DAC selected from the device.

Optical Out from the AK100 into the Optical SPDIF input on my A/V Receiver.

I configured the stereo receiver to use Optical 2 (my TV is plugged into Optical 1 on the receiver).

Windows 10 found the iRiver USB DAC with no problem, and I configured JRiver Media Center to output through the AK100 DAC rather than my Xonar Essence STX sound card.  

On my receiver, when configuring the Optical Audio output, there's the option for using Optical (PCM) or Optical (DDS) or just Optical.

 

I've tried every conceivable configuration, but can't get any audio to output from the stereo.  Am I missing something?  Is this not how the AK100 can be used as a DAC?  I've confirmed the Optical output from the device (which is also the headphone output).  Nothing seems to work.

 

Any ideas?