You can use a stereo HDMI audio extractor to feed the Edifiers:

https://www.amazon.com/J-Tech-Digital-Extractor-Converter-Support/dp/B00YHS5E6Q/ref=sr_1_2_sspa?crid=6TASQQ49KS73

I'm not sure how precise the timing will be with that.

You could also just use an optical splitter (which will probably be synced better), but you'll lose ARC functionality: https://www.amazon.com/dp/B0BW547G3Z/