Have you tried searching the internet?
am getting a couple of hits there....
though not 6-RCA, used a TOSLINK or S/PDIF equipped DAC to connect RPi to home theater audio system... for multi-channel audio experience.
again.... there are many on the wild wild web......
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"
Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"