I have been in touch with a company which fits this kit and they have said the following:
"The Parrot kits contain their own 60 watt class D amplifier, So sound much better that the VW 18 watt standard headunit"
Is this accurate? Thanks.
Amazing, 60 Watt in that little thing, they must have created a new technology to get that much power from something so small. From the information I have, it has a 20W D class amp, but does not state if it's peak or RMS. There is no way it will match a full 4 channel amp inside the radio, even if it's not a great one.
Your best option for playing music from your iphone / ipod is upgrade to an RCD 510, or even better RNS 510 if you want the nav, and get an MDI kit in the car.