This adapter only works one way. From optical to HDMi. So this won’t work.

Thanks for the quick response! Much appreciated. I will use the Sonos adapter on the source TV (optical) end and I will purchase a powered HDMI to Optical splitter for the other end of the cable. https://www.amazon.ca/gp/product/B06XW7HYBP/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 I am hoping this setup will work over the 24’ HDMI cable. 

That will not work either. The Sonos dongle comverts the audio to an ARC signal, not a normal HDMI audio signal. Your Amazon can't convert that back to optical.

Ah ok good point. I found this ARC audio extractor. So TV Optical → Sonos Optical to HDMI ARC adapter → 24’ HDMI cable ARC capable → https://www.amazon.ca/Extractor-Converter-Channel-Adapter-Headphone/dp/B07W9DMPND/ref=asc_df_B07W9DMPND/?tag=bingshopdesk-20&linkCode=df0&hvadid=&hvpos=&hvnetw=o&hvrand=&hvpone=&hvptwo=&hvqmt=e&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=&hvtargid=pla-4584070145532466&psc=1 

→ Denon Optical input

Thoughts on this working properly for digital audio? 

That might work.  It sounds like it would in theory, but I wouldn’t be too surprised if there is handshaking the ARC to optical extractor is looking for that it doesn’t get from the Sonos dongle.   You’re using devices in ways they were not really designed to be used.  I would be prepared to return products if it doesn’t work.

Why not use a longer length optical cable like this?

https://www.mycablemart.com/store/cart.php?m=product_detail&p=3122

Do you already have the HDMI cable in the wall or something like that?

Ya. That is my issue I only have a spare HDMI cable to use. The TV and audio / video rack are separated by finished walls. I am trying to avoid fishing more wires or drywall mudding : ) I will give it a shot and return the adapters if it doesn’t work. I am kicking my butt because I could have ran extra cat 6 cables and then used a Cat 6 balun to extend the optical feed. LIke this one https://www.amazon.com/J-Tech-Digital-Extender-Converter-JTECH-AET1000/dp/B07G5NQCK7/ref=sr_1_5?dchild=1&keywords=jtech+digital+extender&qid=1593006652&sr=8-5

I appreciate your input on this. I will respond and let you know if it works! 

Understood.  This is one of the things I really appreciate living in a single story home for.  It’s usually pretty easy to run wires through the attic for stuff like this.