Switched and unswitched +12v sources for DVB-T.

[notorious]

K.BUS is diagnostics wire that goes to OBD socket. When you connect VCDS it talks to all your devices via that wire. On newer cars a normal CAN bus is used for that.

Start looking at ignition lock diagram on ELSA. One wire will be the wire that keeps +12v with ingnition off until key is removed. But is this what you need? You can switch on RNS-D without key in ignition and listen CDs until it switches itself off by timeout. There must be wire that supplies +12 to CD changer from RNS-D for the period when RND-D actually needs CD changer. For cars of that era this should be done by wire. Same power logic should apply to BOSE amplifier if you have it. Look at the back of your RNS-D. First "Symphony" picture I showed has the "Remote Amp SW. On" callout. Is that what you need?

On "CD" block of wires on your RNS-S there's also "switched" +12v pin. Just like on the line-out block. Take your tester and check.

Check power requirements of stock CD changer or BOSE amp. See power requirements of your DBV tuner. If it needs a lot of power use the pins I recommended to drive a relay that will deliver +12 volts directly from Terminal 30 (constant +12v). The reason why you'll need a relay is because I assume that CD changer and BOSE take power for their operation from a separate constant +12v feed and they only use the RNS-D pin we are discussing to switch themselves on or off based on presence of +12v signal on that wire via internal relay.

You DVB tuner may or may not have two power pins. One for information to switch on and one for actual power as it was not manufactured by Audi.

If you take all the power from the pin we are discussing you may burn RNS-D.

Hope it makes sense.