The composite audio/video on the TV is likely an input and not an output. Here is how I connect my TV to a 2-channel system, and it works extremely well.
Digital output on the TV to this inexpensive DAC,
https://www.bhphotovideo.com/bnh/controller/home?O=&sku=890577&gclid=COPFr8nf5NACFVU7gQodBk0...
then analog L&R from it to the system. The digital output on the TV will need to be set to PCM. You could always use a more expensive DAC, however, I was pleasantly surprised with the sound of this cheap DAC. It is considered the best of the many at that price. Take a look at how it is built.
https://m.youtube.com/watch?v=XVgFIDiZSHk
This will get things working well, and as I said, you can upgrade to a more expensive DAC later if you desire.
Digital output on the TV to this inexpensive DAC,
https://www.bhphotovideo.com/bnh/controller/home?O=&sku=890577&gclid=COPFr8nf5NACFVU7gQodBk0...
then analog L&R from it to the system. The digital output on the TV will need to be set to PCM. You could always use a more expensive DAC, however, I was pleasantly surprised with the sound of this cheap DAC. It is considered the best of the many at that price. Take a look at how it is built.
https://m.youtube.com/watch?v=XVgFIDiZSHk
This will get things working well, and as I said, you can upgrade to a more expensive DAC later if you desire.