It is audible at 60km/h cruising in 5th or 6th gear, and I am not sure whether is exist at higher speed but then wind and road noise might make it impossible to hear.
It is a sound I associate in an old and high mileage car with wear in the driveline which leads to excessive play - my 1986 E28 5er - when you're in a higher gear - 5th - and doing a midget under 60 km/p I constantly hear it. It's annoying and dropping down to a lower gear - 4th cures it.
I haven't tried the same with the E92 and I am sure it would be the same. Yes, with the stereo off you hear it instantaneously. Hope this better explains the condition.
I might drop by at the dealership to have a quick look at things before the warranty runs out in November this year. Can't believe it's three years soon since I got the car.
E92 M3 2007 - ///PE with Test Pipes and BPM Stage II; CF Interior & Splitters; CIC with Connected Drive