I have a n AV receiver in my family room that powers four outdoor speakers. I am going to mount a TV outside and I would like to be able to play the TV audio over the outdoor speakers, but I'm struggling with how to get the audio signal output from the TV to the receiver input. The distance is less than 20 feet laterally, but it's probably close to 50 once I go up through the wall, across the attic, and back down. Can an HDMI cable with ARC run that far, or a digital optical cable? If not, are there other options?

If you have BT on the receiver, you might be able to use it, if not they have BT adapters for older AV non BT receivers.

Just be sure the new tv has BT output of audio or that it accept an adapter to it's audio output that is BT.

monoprice has 50ft HDMI and optical cables.

https://www.monoprice.com/product?p_id=1419

https://www.monoprice.com/product?p_id=15648

Use a high quality HDMI Extender and HDMI cable.
Optical cables have limitations and not so futureproof.

Is there an analog audio output on the tv? You could run that... 50 feet is no problem at all.

You could also buy a digital wireless transmitter of some sort to greatly simplify the set-up though I'd worry about latency being a thing if going wireless.

Were it me I'd work on the analog audio line first over hdmi or some sort of bluetooth add-on system. An RF add-on wireless system would be better than bluetooth, from a latency point of view.

This is an RF type of unknown quality:
https://www.amazon.com/YMOO-Wi...85066693&sr=8-3&th=1