Thanks Erik !
About the sound sensation, i can see that the car was not equiped with the sport exhaust (black oval pipes), so maybe closer to the AMGs with it.
I tried yesterday a C63 (486HP version) and a SLS on track. Incredible machines.
A famous car journalist in France told be the RS5 was really fun to drive. The first Audi that makes you completely forget you are driving a 4WD car. Of course with the quattro differencial option.
The only thing he was upset with was the S-tronic system in full automatic mode. Not clever enough, so you have to be almost all the time in manuel mode. Too lazy in confort mode, too nervous in sport mode. He prefers the AMG system (which ever old system in the C or new one with dual clutch in the SLS), really doing what you want to in full automatic mode. Able to be very "sport" or give you one second later the 7nd gear with a 2000RPM when crossing a village....