Aftermarket Headunit Fitting

Bose use extra amps to power front, rear and sub. If you connect an aftermarket headunit to these using the low level amp output (to front and rear) it will sound near enough the same as your standard headunit as it is using the same Bose amps to generate the sound.

If you get the wrong adapter harness (none Bose uses only one amp for the rear + sub and uses the headunits own amp for the front) you will supply the front Bose amp with high level amplified speaker outputs which will cause distortion and sound cr@p .

I know of this happening to people that have gone to Halfords so maybe this is what they are on about. With the right harness it should sound the same but no better & the sub will still work.

There are different Bose harnesses.

Auto leads (Halfords tend to use them) supply more than one Bose labelled harness for Audi depending on what you want to do with the headunit and how many, if any RCA outputs your new radio has (0, 2 or 4). Just make sure it connects up to the low-level outputs or RCA.

One harness if used can be wired incorrectly & will send high level to the front amp even though it says Bose on it, one member on this forum has already had this problem even though they ordered Bose.

And one converts 2 outputs from the radio into 4 which might be a detriment to sound quality because there is no fader control.

You can also get horrible clicks from the RCA input adapter when changing CD track, setting the volume to zero etc - see recent post for A6 with Bose by Rich DJ