Symphony II to Dynavin sound question

[DeVille]

Hi. I know there are several threads about this, but from my look a little more unspecified and no good answers (for me atleast that i could find...)

I have a Audi A4 B7 (2007), this had a Symphony II (1Din with CD) I've bought a Dynavin D99 and modified for a 2Din. (Non bose)
Problem is like others have written, no rear sound.

Rear amp has power, i've tried both to measure power and just take plug out and in and hear the relay switch.
There is also a small "zumming" noice from the rear speakers.

I think it may be that the dynavin does not send sound to the amp. The Symphony have special output for the amp, 2 positive, one for each side and a common ground.
My guess, is since the dynavin got seperate output for audiosignal, that this is not the correct setup "out of the box" between Symphony and Dynavin...

So, in my head, the solution is to either:
- Connect rear left and right speaker positivt from Dynavin to the two positive OEM car cable, and the two negative from Dynavin to the common negative. (hi output, sounds wrong...)
- Cut the heads of the rear signal cabels, use positive's to positives OEM car, negative to common negative. (low output, sounds more right...)

Does this sounds right?
If i'm right, is there an adapter that does this for me?

[DeVille]

To answer myself (Go figure...)

So, in my head, the solution is to either:
- Connect rear left and right speaker positivt from Dynavin to the two positive OEM car cable, and the two negative from Dynavin to the common negative. (hi output, sounds wrong...)

was almost correct. connected positive from rear left and right to the OEM car cable (Green and yellow), all good :-)