I've been looking all over for any info on this. I'd like to remove my head unit but keep the factory amp in the back ('04 Golf) with the PC being the only source running to it. The info I need includes: (I put what I know so far as well in case it helps others)
- How to power on/off the amp. (Not quite sure where to begin for this. I'll be using that Opus 90w power supply. Can that provide what's needed to signal power-up?)
- How to run in the line level from PC (this I found at vwvortex.com):
Gray Amp connector (Speaker level Input from HU) Most people tap the rear lines for Subs.
15 - LR
17 - RR
21 - LF
23 + RF
24 - RF
if you need to power up the amp (assuming its the same as my 03 A4 with bose), you just need 12V with almost no amps. run it into the switched 12V line. as far as tapping the rear lines, you can use radioshack wire taps and run the spkr level through a line level converter to get line level sound for your sub/amp.
Post back if you have more specific questions.
You cannot use speaker level output to tap into. It is only good with LLC (Line Level Converter) to use with a sub amp. It works one way and not the other - from speaker level to line level.
What you need to find is how the amp is controlled and what kind of input does it take. Where does the volume change - in the amp or the headunit (some hedunits control amp digitally)? Is the input balanced (+/- with a mid point in the ground) or unbalanced (- is the ground)? PC's output is unbalanced.
Get on VW forum and ask them. I'm sure plenty people replaced their headunits and tried to keep the stock amp. Essentially, this is what you're doing.
The remote turn-on is not hard. You can simply connect it to the ACC wire to get you going, provided there is a remote turn-on input on the amp.