Originally Posted by parapaul
Once coded from Professional to HiFi settings, the head unit doesn't output heavily EQ'd speaker level signals, it outputs a flat low level signal.
Still trying to find out if I can just solder an RCA to the end of the speaker wires or whether I need to ground the sleeve.
The coding changes the way the speaker outputs are driven; into a single ended configuration. IE. One pair of output transistors are no longer driven.
I would say technically, it would be possible to directly connect the RCA plug as long as you know which of the original speaker connections remains as 'live' and which one is now 'earth'.
I would be inclined to connect the 'earthy' side to the RCA plug outer via a low value 2Watt resistor. (Any standard value in the range 22 to 47ohm). That way, if anything untoward happens, the output stage transistors won't get fried.....
You may still need a loading resistor on the speaker output but it all depends on the HU internal circuit.
It shouldn't cause a problem if you do fit them.