Thread: Replacing Audi A4 Head Unit with Sony?

Hi,

I am after changing my standard Audi A4 Head Unit that came with the car with a standard Sony one.

However, I heard somewhere that the rear speakers won't work after doing this due to the Bose Amp

Can someone advise me on this please?

Thanks,

Nick

Depends if you have Bose or not.
Non Bose has the front speakers running off the HU and the rears use a tiny amp bolted to the nearside speaker. This amp should be bypassed by just running new speaker cable directly from the new HU to the rears. You can buy an adapter that will allow you to plug the rear RCA's from the Sony into the loom for the rear amp, but you compromise both quality and volume by doing this as you will have a lot more power now going to the fronts.
With the Bose system all the speakers are separately amped, and they are very low impedance speakers so you cannot drive them directly from the HU. You have to use the adapter PC9-410 and only if the Sony has both front & rear pre-outs (RCA's). If it doesn't then you have to use the speaker input adapter PC9-408 which uses a hi-lo converter to take the high level speaker outputs from the Sony back down to pre-amp level so they can be reamplified again by the Bose amp. This process is not good for quality and can result in interference and hiss.