My original TV was a Toshiba and was connected to the iRV66 through the RCA audio out pin jacks. With that, the SRC button was set to TV Audio and worked. Finding TVs anymore with the RCA audio out jacks is a rarity.
The dealer replaced the TV (because there was an annoying buzz in the surround sound which I had to prove to the dealer was caused by a defective Toshiba TV) with a Furrion, which does have the RCA audio outputs needed to connect with the iRV66.
Prior to the TV exchange, I had connected the two units with an OIS (optical) cable and the SRC(iRV66) button then, had to be set at the DCC/??? position to work with that hookup between the components.
Alas, the Furrion TV does not have a OIS output, but, it does work with the original RCA cables and SRC set to TV Audio!