Thanks very much for your comments and thoughts on this matter, much appreciated.
I haven't managed to get to my dealer to have them print out the full specification for my car to see what 6xx options I have however on the original paperwork I've found a list which I think is pretty comprehensive and I see 6FL (USB-audio interface) listed but NOT the 6NF (smartphone integration) option
So my understanding is:
- No 6NF = no ability to play music from the iPhone even with the cradle
- The cradle will charge the phone and allow better cellphone reception
- Unplug the cradle and use the new cable (per comments from msimon18 and rmorin49) and I'll be able to use the iPhone like a USB audio device and also it'll charge from the USB power
Is this right or have I lost the plot?