I think if you connect behind the amplifier you will lose the benefit of the amplification of the Parrot signal, and the sound could be even quieter. I think that connecting behind the radio, and before the amplifier, is the correct way to go. I also have a Parrot kit installed (the earlier CK3000, non-EVO), and I agree that the sound is quieter than the radio's, but you can adjust the volume during a call using the volume buttons on the steering wheel (another advantage of connecting before the amplifier). I was advised that the radio output is already at speaker level (so no attenuator is required - as you've discovered), so maybe the amplifier simply provides better tone control and the ability to drive better speakers, and in fact it might actually attenuate the signal - not really sure! If that is the case, I suppose you might benefit from connecting after the amplifier. However, I was definitely advised that the Parrot kit should sit between the radio and the amplifier.
I used a harness adapter from SIOcomminucations.co.uk (
http://www.siocommunications.co.uk/S...SOT-046&page=1). I had to add an ignition-controlled live feed, but that was easy to take from the front cigarette lighter. Terry at SIO was very helpful, so I would suggest you check with him that this part is right for your kit and your car. I note that his website says they are closed until 20th August.