Make sure the active cable can support ARC. We had problems with 8K Ruipro cables that the electrician supplied and 7 out of 8 didn't work and didn't pass testing with Fox and Hound older 4K tester. They were 33 foot or 50 foot versions. All were replaced with Ethereal MHX series and worked fine. These were just for ARC so didn't need 4k/8k video and the heavier gauge cable worked fine.
Many of the optical cables have a copper wire that runs alongside the fiber for ARC and limits its length for ARC. If going longer use an HDMI extender with CAT 5/6 that can handle ARC. I know Ethereal lists the length that their active optical cables don't work with ARC but it is not that far, 10 meters? Brent can answer that. Unfortunately, a lot of companies making active optical cables don't state what their length limit is if using ARC.
