A:Answer I am going to try to address this myself. When I was at the store, an employee recommended using an HDMI audio extractor (https://www.bestbuy.com/site/insignia-hdmi-audio-extractor-black/6324750.p?skuId=6324750&ref=212&loc=1&extStoreId=512&ref=212&loc=1&gclid=Cj0KCQiAyJOBBhDCARIsAJG2h5d8bPJbH7pi9VMdC57FqbnmWVcT4BrPM_ZsNvtKqZwsRzL5QvNlMLMaAhocEALw_wcB&gclsrc=aw.ds), available for about $50.
using the audio extractor, you can plug the firestick into the input of the extractor, which will tap the audio and send it to an optical output you can connect to the Yamaha soundbar. The video signal will pass through an HDMI output on the extractor to your TV. This will leave the HDMI in on the soundbar free to accept the signal from your TV.