Hi @Asher77,
Greetings from the Roku Community!
If you're having trouble connecting a plain audio/video cable (like RCA) from your Roku TV to your stereo system, make sure you're connecting to an output on the TV, not an input, and check the audio output settings on the Roku TV and your stereo receiver.
We hope this helps.
Cheers,
The Roku Community Team
John
Roku Community Moderator