The sub out connection gives you a volume controlled output so don’t use that. Use rec out from either av or stream din socket which is a line level output, so you can turn down the volume on the sn without impacting the headphone amp.
You will need to buy a 5 pin din to 4 x rca plugs interconnect; 2 will be “in” and 2 will be “out”.
The cable you need:
[edited to clarify] what you actually need is din to 2 rca with the rca being output also known as rec or record. However there have been instances of people buying the wrong cable ie theirs isnt rec/out but play/in. If you buy the 4 rca then 2 of them will always be the output ones that you need.
