I successfully set up the project on two RPI3s and (after a brief moment of stupidity) verified audio from both HDMI and the earphone jack on the second Pi. Smooth sailing so far.
After making sure that everything was working, I connected a HiFiBerry Amp2 to my second RPi3:
https://www.hifiberry.com/shop/boards/hifiberry-amp2/
And connected these speakers:
https://smile.amazon.com/gp/product/B00378KMEG/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
As recommended by the HiFiBerry specs, I’m using an 18v power supply to power both the Pi3 and the Amp. The HiFiBerry Amp2 has a single green LED lit on its top and all LEDs on the Pi3 are illumined. I can see in the balenaSound dashboard that the second Pi is streaming audio, but I’m not getting any sound from the speakers. I wrote to HiFiBerry support, sent them the above info, and asked if they had any troubleshooting suggestions for me. Their response was:
I’m not familiar with this distribution. You probably need to configure it first:
https://www.hifiberry.com/docs/software/configuring-linux-3-18-x/Alternatively have a look at HiFiBerryOS that will automatically detect the card: https://www.hifiberry.com/os
Evidently they saw no problems with the hardware and suspect that it’s just a config issue. I thought it might be smart to ask for guidance before going any further. Any guidance much appreciated. Thanks!