Altezza sound system issue

[Irmi]

Hi guys,

I‘m no good with sound systems, so I‘m hoping maybe one of you can help me out with this?

So I got my Japan imported Altezza, and it came with a custom radio/ navigation/multimedia system. After pulling out the Japanese toll system, TV receiver and *whatever* aftermarket stuff you just can’t use in Europe, I finally managed to swap in a new radio (sony xavax3250) and get it working with the built in speakers (via ISO Adapter to original connector).

Problem is, there is something like white noise permanently present from the moment it is switched on, remaining hearable with music and getting louder with the volume. I assume it is because the radio output is already amplified, but going to the built in amplifier. Probably the easy way would be to search for the original amplifier and bypass it to connect the speakers directly.

But it seems like the higher-end original sound system is built in, and I would really prefer to somehow get it working again. The radio has also A/V plugs (Front / Rear / Sub), but I don’t know how to connect those as from the vehicle there are only the „normal“ FR/FL/RR/RL lines on the original car connector (pinning attached).

Do you have experience with similar systems? Any hint how to get it running is really appreciated!

BR Irmi